blob: e8dfa6c3ef420bea1913bcf875e91a2915f753fd [file] [log] [blame]
/*
** 2018 May 08
**
** The author disclaims copyright to this source code. In place of
** a legal notice, here is a blessing:
**
** May you do good and not evil.
** May you find forgiveness for yourself and forgive others.
** May you share freely, never taking more than you give.
**
*************************************************************************
*/
#include "sqliteInt.h"
#ifndef SQLITE_OMIT_WINDOWFUNC
/*
** SELECT REWRITING
**
** Any SELECT statement that contains one or more window functions in
** either the select list or ORDER BY clause (the only two places window
** functions may be used) is transformed by function sqlite3WindowRewrite()
** in order to support window function processing. For example, with the
** schema:
**
** CREATE TABLE t1(a, b, c, d, e, f, g);
**
** the statement:
**
** SELECT a+1, max(b) OVER (PARTITION BY c ORDER BY d) FROM t1 ORDER BY e;
**
** is transformed to:
**
** SELECT a+1, max(b) OVER (PARTITION BY c ORDER BY d) FROM (
** SELECT a, e, c, d, b FROM t1 ORDER BY c, d
** ) ORDER BY e;
**
** The flattening optimization is disabled when processing this transformed
** SELECT statement. This allows the implementation of the window function
** (in this case max()) to process rows sorted in order of (c, d), which
** makes things easier for obvious reasons. More generally:
**
** * FROM, WHERE, GROUP BY and HAVING clauses are all moved to
** the sub-query.
**
** * ORDER BY, LIMIT and OFFSET remain part of the parent query.
**
** * Terminals from each of the expression trees that make up the
** select-list and ORDER BY expressions in the parent query are
** selected by the sub-query. For the purposes of the transformation,
** terminals are column references and aggregate functions.
**
** If there is more than one window function in the SELECT that uses
** the same window declaration (the OVER bit), then a single scan may
** be used to process more than one window function. For example:
**
** SELECT max(b) OVER (PARTITION BY c ORDER BY d),
** min(e) OVER (PARTITION BY c ORDER BY d)
** FROM t1;
**
** is transformed in the same way as the example above. However:
**
** SELECT max(b) OVER (PARTITION BY c ORDER BY d),
** min(e) OVER (PARTITION BY a ORDER BY b)
** FROM t1;
**
** Must be transformed to:
**
** SELECT max(b) OVER (PARTITION BY c ORDER BY d) FROM (
** SELECT e, min(e) OVER (PARTITION BY a ORDER BY b), c, d, b FROM
** SELECT a, e, c, d, b FROM t1 ORDER BY a, b
** ) ORDER BY c, d
** ) ORDER BY e;
**
** so that both min() and max() may process rows in the order defined by
** their respective window declarations.
**
** INTERFACE WITH SELECT.C
**
** When processing the rewritten SELECT statement, code in select.c calls
** sqlite3WhereBegin() to begin iterating through the results of the
** sub-query, which is always implemented as a co-routine. It then calls
** sqlite3WindowCodeStep() to process rows and finish the scan by calling
** sqlite3WhereEnd().
**
** sqlite3WindowCodeStep() generates VM code so that, for each row returned
** by the sub-query a sub-routine (OP_Gosub) coded by select.c is invoked.
** When the sub-routine is invoked:
**
** * The results of all window-functions for the row are stored
** in the associated Window.regResult registers.
**
** * The required terminal values are stored in the current row of
** temp table Window.iEphCsr.
**
** In some cases, depending on the window frame and the specific window
** functions invoked, sqlite3WindowCodeStep() caches each entire partition
** in a temp table before returning any rows. In other cases it does not.
** This detail is encapsulated within this file, the code generated by
** select.c is the same in either case.
**
** BUILT-IN WINDOW FUNCTIONS
**
** This implementation features the following built-in window functions:
**
** row_number()
** rank()
** dense_rank()
** percent_rank()
** cume_dist()
** ntile(N)
** lead(expr [, offset [, default]])
** lag(expr [, offset [, default]])
** first_value(expr)
** last_value(expr)
** nth_value(expr, N)
**
** These are the same built-in window functions supported by Postgres.
** Although the behaviour of aggregate window functions (functions that
** can be used as either aggregates or window funtions) allows them to
** be implemented using an API, built-in window functions are much more
** esoteric. Additionally, some window functions (e.g. nth_value())
** may only be implemented by caching the entire partition in memory.
** As such, some built-in window functions use the same API as aggregate
** window functions and some are implemented directly using VDBE
** instructions. Additionally, for those functions that use the API, the
** window frame is sometimes modified before the SELECT statement is
** rewritten. For example, regardless of the specified window frame, the
** row_number() function always uses:
**
** ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW
**
** See sqlite3WindowUpdate() for details.
**
** As well as some of the built-in window functions, aggregate window
** functions min() and max() are implemented using VDBE instructions if
** the start of the window frame is declared as anything other than
** UNBOUNDED PRECEDING.
*/
/*
** Implementation of built-in window function row_number(). Assumes that the
** window frame has been coerced to:
**
** ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW
*/
static void row_numberStepFunc(
sqlite3_context *pCtx,
int nArg,
sqlite3_value **apArg
){
i64 *p = (i64*)sqlite3_aggregate_context(pCtx, sizeof(*p));
if( p ) (*p)++;
UNUSED_PARAMETER(nArg);
UNUSED_PARAMETER(apArg);
}
static void row_numberValueFunc(sqlite3_context *pCtx){
i64 *p = (i64*)sqlite3_aggregate_context(pCtx, sizeof(*p));
sqlite3_result_int64(pCtx, (p ? *p : 0));
}
/*
** Context object type used by rank(), dense_rank(), percent_rank() and
** cume_dist().
*/
struct CallCount {
i64 nValue;
i64 nStep;
i64 nTotal;
};
/*
** Implementation of built-in window function dense_rank(). Assumes that
** the window frame has been set to:
**
** RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW
*/
static void dense_rankStepFunc(
sqlite3_context *pCtx,
int nArg,
sqlite3_value **apArg
){
struct CallCount *p;
p = (struct CallCount*)sqlite3_aggregate_context(pCtx, sizeof(*p));
if( p ) p->nStep = 1;
UNUSED_PARAMETER(nArg);
UNUSED_PARAMETER(apArg);
}
static void dense_rankValueFunc(sqlite3_context *pCtx){
struct CallCount *p;
p = (struct CallCount*)sqlite3_aggregate_context(pCtx, sizeof(*p));
if( p ){
if( p->nStep ){
p->nValue++;
p->nStep = 0;
}
sqlite3_result_int64(pCtx, p->nValue);
}
}
/*
** Implementation of built-in window function nth_value(). This
** implementation is used in "slow mode" only - when the EXCLUDE clause
** is not set to the default value "NO OTHERS".
*/
struct NthValueCtx {
i64 nStep;
sqlite3_value *pValue;
};
static void nth_valueStepFunc(
sqlite3_context *pCtx,
int nArg,
sqlite3_value **apArg
){
struct NthValueCtx *p;
p = (struct NthValueCtx*)sqlite3_aggregate_context(pCtx, sizeof(*p));
if( p ){
i64 iVal;
switch( sqlite3_value_numeric_type(apArg[1]) ){
case SQLITE_INTEGER:
iVal = sqlite3_value_int64(apArg[1]);
break;
case SQLITE_FLOAT: {
double fVal = sqlite3_value_double(apArg[1]);
if( ((i64)fVal)!=fVal ) goto error_out;
iVal = (i64)fVal;
break;
}
default:
goto error_out;
}
if( iVal<=0 ) goto error_out;
p->nStep++;
if( iVal==p->nStep ){
p->pValue = sqlite3_value_dup(apArg[0]);
if( !p->pValue ){
sqlite3_result_error_nomem(pCtx);
}
}
}
UNUSED_PARAMETER(nArg);
UNUSED_PARAMETER(apArg);
return;
error_out:
sqlite3_result_error(
pCtx, "second argument to nth_value must be a positive integer", -1
);
}
static void nth_valueFinalizeFunc(sqlite3_context *pCtx){
struct NthValueCtx *p;
p = (struct NthValueCtx*)sqlite3_aggregate_context(pCtx, 0);
if( p && p->pValue ){
sqlite3_result_value(pCtx, p->pValue);
sqlite3_value_free(p->pValue);
p->pValue = 0;
}
}
#define nth_valueInvFunc noopStepFunc
#define nth_valueValueFunc noopValueFunc
static void first_valueStepFunc(
sqlite3_context *pCtx,
int nArg,
sqlite3_value **apArg
){
struct NthValueCtx *p;
p = (struct NthValueCtx*)sqlite3_aggregate_context(pCtx, sizeof(*p));
if( p && p->pValue==0 ){
p->pValue = sqlite3_value_dup(apArg[0]);
if( !p->pValue ){
sqlite3_result_error_nomem(pCtx);
}
}
UNUSED_PARAMETER(nArg);
UNUSED_PARAMETER(apArg);
}
static void first_valueFinalizeFunc(sqlite3_context *pCtx){
struct NthValueCtx *p;
p = (struct NthValueCtx*)sqlite3_aggregate_context(pCtx, sizeof(*p));
if( p && p->pValue ){
sqlite3_result_value(pCtx, p->pValue);
sqlite3_value_free(p->pValue);
p->pValue = 0;
}
}
#define first_valueInvFunc noopStepFunc
#define first_valueValueFunc noopValueFunc
/*
** Implementation of built-in window function rank(). Assumes that
** the window frame has been set to:
**
** RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW
*/
static void rankStepFunc(
sqlite3_context *pCtx,
int nArg,
sqlite3_value **apArg
){
struct CallCount *p;
p = (struct CallCount*)sqlite3_aggregate_context(pCtx, sizeof(*p));
if( p ){
p->nStep++;
if( p->nValue==0 ){
p->nValue = p->nStep;
}
}
UNUSED_PARAMETER(nArg);
UNUSED_PARAMETER(apArg);
}
static void rankValueFunc(sqlite3_context *pCtx){
struct CallCount *p;
p = (struct CallCount*)sqlite3_aggregate_context(pCtx, sizeof(*p));
if( p ){
sqlite3_result_int64(pCtx, p->nValue);
p->nValue = 0;
}
}
/*
** Implementation of built-in window function percent_rank(). Assumes that
** the window frame has been set to:
**
** GROUPS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING
*/
static void percent_rankStepFunc(
sqlite3_context *pCtx,
int nArg,
sqlite3_value **apArg
){
struct CallCount *p;
UNUSED_PARAMETER(nArg); assert( nArg==0 );
UNUSED_PARAMETER(apArg);
p = (struct CallCount*)sqlite3_aggregate_context(pCtx, sizeof(*p));
if( p ){
p->nTotal++;
}
}
static void percent_rankInvFunc(
sqlite3_context *pCtx,
int nArg,
sqlite3_value **apArg
){
struct CallCount *p;
UNUSED_PARAMETER(nArg); assert( nArg==0 );
UNUSED_PARAMETER(apArg);
p = (struct CallCount*)sqlite3_aggregate_context(pCtx, sizeof(*p));
p->nStep++;
}
static void percent_rankValueFunc(sqlite3_context *pCtx){
struct CallCount *p;
p = (struct CallCount*)sqlite3_aggregate_context(pCtx, sizeof(*p));
if( p ){
p->nValue = p->nStep;
if( p->nTotal>1 ){
double r = (double)p->nValue / (double)(p->nTotal-1);
sqlite3_result_double(pCtx, r);
}else{
sqlite3_result_double(pCtx, 0.0);
}
}
}
#define percent_rankFinalizeFunc percent_rankValueFunc
/*
** Implementation of built-in window function cume_dist(). Assumes that
** the window frame has been set to:
**
** GROUPS BETWEEN 1 FOLLOWING AND UNBOUNDED FOLLOWING
*/
static void cume_distStepFunc(
sqlite3_context *pCtx,
int nArg,
sqlite3_value **apArg
){
struct CallCount *p;
UNUSED_PARAMETER(nArg); assert( nArg==0 );
UNUSED_PARAMETER(apArg);
p = (struct CallCount*)sqlite3_aggregate_context(pCtx, sizeof(*p));
if( p ){
p->nTotal++;
}
}
static void cume_distInvFunc(
sqlite3_context *pCtx,
int nArg,
sqlite3_value **apArg
){
struct CallCount *p;
UNUSED_PARAMETER(nArg); assert( nArg==0 );
UNUSED_PARAMETER(apArg);
p = (struct CallCount*)sqlite3_aggregate_context(pCtx, sizeof(*p));
p->nStep++;
}
static void cume_distValueFunc(sqlite3_context *pCtx){
struct CallCount *p;
p = (struct CallCount*)sqlite3_aggregate_context(pCtx, 0);
if( p ){
double r = (double)(p->nStep) / (double)(p->nTotal);
sqlite3_result_double(pCtx, r);
}
}
#define cume_distFinalizeFunc cume_distValueFunc
/*
** Context object for ntile() window function.
*/
struct NtileCtx {
i64 nTotal; /* Total rows in partition */
i64 nParam; /* Parameter passed to ntile(N) */
i64 iRow; /* Current row */
};
/*
** Implementation of ntile(). This assumes that the window frame has
** been coerced to:
**
** ROWS CURRENT ROW AND UNBOUNDED FOLLOWING
*/
static void ntileStepFunc(
sqlite3_context *pCtx,
int nArg,
sqlite3_value **apArg
){
struct NtileCtx *p;
assert( nArg==1 ); UNUSED_PARAMETER(nArg);
p = (struct NtileCtx*)sqlite3_aggregate_context(pCtx, sizeof(*p));
if( p ){
if( p->nTotal==0 ){
p->nParam = sqlite3_value_int64(apArg[0]);
if( p->nParam<=0 ){
sqlite3_result_error(
pCtx, "argument of ntile must be a positive integer", -1
);
}
}
p->nTotal++;
}
}
static void ntileInvFunc(
sqlite3_context *pCtx,
int nArg,
sqlite3_value **apArg
){
struct NtileCtx *p;
assert( nArg==1 ); UNUSED_PARAMETER(nArg);
UNUSED_PARAMETER(apArg);
p = (struct NtileCtx*)sqlite3_aggregate_context(pCtx, sizeof(*p));
p->iRow++;
}
static void ntileValueFunc(sqlite3_context *pCtx){
struct NtileCtx *p;
p = (struct NtileCtx*)sqlite3_aggregate_context(pCtx, sizeof(*p));
if( p && p->nParam>0 ){
int nSize = (p->nTotal / p->nParam);
if( nSize==0 ){
sqlite3_result_int64(pCtx, p->iRow+1);
}else{
i64 nLarge = p->nTotal - p->nParam*nSize;
i64 iSmall = nLarge*(nSize+1);
i64 iRow = p->iRow;
assert( (nLarge*(nSize+1) + (p->nParam-nLarge)*nSize)==p->nTotal );
if( iRow<iSmall ){
sqlite3_result_int64(pCtx, 1 + iRow/(nSize+1));
}else{
sqlite3_result_int64(pCtx, 1 + nLarge + (iRow-iSmall)/nSize);
}
}
}
}
#define ntileFinalizeFunc ntileValueFunc
/*
** Context object for last_value() window function.
*/
struct LastValueCtx {
sqlite3_value *pVal;
int nVal;
};
/*
** Implementation of last_value().
*/
static void last_valueStepFunc(
sqlite3_context *pCtx,
int nArg,
sqlite3_value **apArg
){
struct LastValueCtx *p;
UNUSED_PARAMETER(nArg);
p = (struct LastValueCtx*)sqlite3_aggregate_context(pCtx, sizeof(*p));
if( p ){
sqlite3_value_free(p->pVal);
p->pVal = sqlite3_value_dup(apArg[0]);
if( p->pVal==0 ){
sqlite3_result_error_nomem(pCtx);
}else{
p->nVal++;
}
}
}
static void last_valueInvFunc(
sqlite3_context *pCtx,
int nArg,
sqlite3_value **apArg
){
struct LastValueCtx *p;
UNUSED_PARAMETER(nArg);
UNUSED_PARAMETER(apArg);
p = (struct LastValueCtx*)sqlite3_aggregate_context(pCtx, sizeof(*p));
if( ALWAYS(p) ){
p->nVal--;
if( p->nVal==0 ){
sqlite3_value_free(p->pVal);
p->pVal = 0;
}
}
}
static void last_valueValueFunc(sqlite3_context *pCtx){
struct LastValueCtx *p;
p = (struct LastValueCtx*)sqlite3_aggregate_context(pCtx, 0);
if( p && p->pVal ){
sqlite3_result_value(pCtx, p->pVal);
}
}
static void last_valueFinalizeFunc(sqlite3_context *pCtx){
struct LastValueCtx *p;
p = (struct LastValueCtx*)sqlite3_aggregate_context(pCtx, sizeof(*p));
if( p && p->pVal ){
sqlite3_result_value(pCtx, p->pVal);
sqlite3_value_free(p->pVal);
p->pVal = 0;
}
}
/*
** Static names for the built-in window function names. These static
** names are used, rather than string literals, so that FuncDef objects
** can be associated with a particular window function by direct
** comparison of the zName pointer. Example:
**
** if( pFuncDef->zName==row_valueName ){ ... }
*/
static const char row_numberName[] = "row_number";
static const char dense_rankName[] = "dense_rank";
static const char rankName[] = "rank";
static const char percent_rankName[] = "percent_rank";
static const char cume_distName[] = "cume_dist";
static const char ntileName[] = "ntile";
static const char last_valueName[] = "last_value";
static const char nth_valueName[] = "nth_value";
static const char first_valueName[] = "first_value";
static const char leadName[] = "lead";
static const char lagName[] = "lag";
/*
** No-op implementations of xStep() and xFinalize(). Used as place-holders
** for built-in window functions that never call those interfaces.
**
** The noopValueFunc() is called but is expected to do nothing. The
** noopStepFunc() is never called, and so it is marked with NO_TEST to
** let the test coverage routine know not to expect this function to be
** invoked.
*/
static void noopStepFunc( /*NO_TEST*/
sqlite3_context *p, /*NO_TEST*/
int n, /*NO_TEST*/
sqlite3_value **a /*NO_TEST*/
){ /*NO_TEST*/
UNUSED_PARAMETER(p); /*NO_TEST*/
UNUSED_PARAMETER(n); /*NO_TEST*/
UNUSED_PARAMETER(a); /*NO_TEST*/
assert(0); /*NO_TEST*/
} /*NO_TEST*/
static void noopValueFunc(sqlite3_context *p){ UNUSED_PARAMETER(p); /*no-op*/ }
/* Window functions that use all window interfaces: xStep, xFinal,
** xValue, and xInverse */
#define WINDOWFUNCALL(name,nArg,extra) { \
nArg, (SQLITE_UTF8|SQLITE_FUNC_WINDOW|extra), 0, 0, \
name ## StepFunc, name ## FinalizeFunc, name ## ValueFunc, \
name ## InvFunc, name ## Name, {0} \
}
/* Window functions that are implemented using bytecode and thus have
** no-op routines for their methods */
#define WINDOWFUNCNOOP(name,nArg,extra) { \
nArg, (SQLITE_UTF8|SQLITE_FUNC_WINDOW|extra), 0, 0, \
noopStepFunc, noopValueFunc, noopValueFunc, \
noopStepFunc, name ## Name, {0} \
}
/* Window functions that use all window interfaces: xStep, the
** same routine for xFinalize and xValue and which never call
** xInverse. */
#define WINDOWFUNCX(name,nArg,extra) { \
nArg, (SQLITE_UTF8|SQLITE_FUNC_WINDOW|extra), 0, 0, \
name ## StepFunc, name ## ValueFunc, name ## ValueFunc, \
noopStepFunc, name ## Name, {0} \
}
/*
** Register those built-in window functions that are not also aggregates.
*/
void sqlite3WindowFunctions(void){
static FuncDef aWindowFuncs[] = {
WINDOWFUNCX(row_number, 0, 0),
WINDOWFUNCX(dense_rank, 0, 0),
WINDOWFUNCX(rank, 0, 0),
WINDOWFUNCALL(percent_rank, 0, 0),
WINDOWFUNCALL(cume_dist, 0, 0),
WINDOWFUNCALL(ntile, 1, 0),
WINDOWFUNCALL(last_value, 1, 0),
WINDOWFUNCALL(nth_value, 2, 0),
WINDOWFUNCALL(first_value, 1, 0),
WINDOWFUNCNOOP(lead, 1, 0),
WINDOWFUNCNOOP(lead, 2, 0),
WINDOWFUNCNOOP(lead, 3, 0),
WINDOWFUNCNOOP(lag, 1, 0),
WINDOWFUNCNOOP(lag, 2, 0),
WINDOWFUNCNOOP(lag, 3, 0),
};
sqlite3InsertBuiltinFuncs(aWindowFuncs, ArraySize(aWindowFuncs));
}
static Window *windowFind(Parse *pParse, Window *pList, const char *zName){
Window *p;
for(p=pList; p; p=p->pNextWin){
if( sqlite3StrICmp(p->zName, zName)==0 ) break;
}
if( p==0 ){
sqlite3ErrorMsg(pParse, "no such window: %s", zName);
}
return p;
}
/*
** This function is called immediately after resolving the function name
** for a window function within a SELECT statement. Argument pList is a
** linked list of WINDOW definitions for the current SELECT statement.
** Argument pFunc is the function definition just resolved and pWin
** is the Window object representing the associated OVER clause. This
** function updates the contents of pWin as follows:
**
** * If the OVER clause refered to a named window (as in "max(x) OVER win"),
** search list pList for a matching WINDOW definition, and update pWin
** accordingly. If no such WINDOW clause can be found, leave an error
** in pParse.
**
** * If the function is a built-in window function that requires the
** window to be coerced (see "BUILT-IN WINDOW FUNCTIONS" at the top
** of this file), pWin is updated here.
*/
void sqlite3WindowUpdate(
Parse *pParse,
Window *pList, /* List of named windows for this SELECT */
Window *pWin, /* Window frame to update */
FuncDef *pFunc /* Window function definition */
){
if( pWin->zName && pWin->eFrmType==0 ){
Window *p = windowFind(pParse, pList, pWin->zName);
if( p==0 ) return;
pWin->pPartition = sqlite3ExprListDup(pParse->db, p->pPartition, 0);
pWin->pOrderBy = sqlite3ExprListDup(pParse->db, p->pOrderBy, 0);
pWin->pStart = sqlite3ExprDup(pParse->db, p->pStart, 0);
pWin->pEnd = sqlite3ExprDup(pParse->db, p->pEnd, 0);
pWin->eStart = p->eStart;
pWin->eEnd = p->eEnd;
pWin->eFrmType = p->eFrmType;
pWin->eExclude = p->eExclude;
}else{
sqlite3WindowChain(pParse, pWin, pList);
}
if( (pWin->eFrmType==TK_RANGE)
&& (pWin->pStart || pWin->pEnd)
&& (pWin->pOrderBy==0 || pWin->pOrderBy->nExpr!=1)
){
sqlite3ErrorMsg(pParse,
"RANGE with offset PRECEDING/FOLLOWING requires one ORDER BY expression"
);
}else
if( pFunc->funcFlags & SQLITE_FUNC_WINDOW ){
sqlite3 *db = pParse->db;
if( pWin->pFilter ){
sqlite3ErrorMsg(pParse,
"FILTER clause may only be used with aggregate window functions"
);
}else{
struct WindowUpdate {
const char *zFunc;
int eFrmType;
int eStart;
int eEnd;
} aUp[] = {
{ row_numberName, TK_ROWS, TK_UNBOUNDED, TK_CURRENT },
{ dense_rankName, TK_RANGE, TK_UNBOUNDED, TK_CURRENT },
{ rankName, TK_RANGE, TK_UNBOUNDED, TK_CURRENT },
{ percent_rankName, TK_GROUPS, TK_CURRENT, TK_UNBOUNDED },
{ cume_distName, TK_GROUPS, TK_FOLLOWING, TK_UNBOUNDED },
{ ntileName, TK_ROWS, TK_CURRENT, TK_UNBOUNDED },
{ leadName, TK_ROWS, TK_UNBOUNDED, TK_UNBOUNDED },
{ lagName, TK_ROWS, TK_UNBOUNDED, TK_CURRENT },
};
int i;
for(i=0; i<ArraySize(aUp); i++){
if( pFunc->zName==aUp[i].zFunc ){
sqlite3ExprDelete(db, pWin->pStart);
sqlite3ExprDelete(db, pWin->pEnd);
pWin->pEnd = pWin->pStart = 0;
pWin->eFrmType = aUp[i].eFrmType;
pWin->eStart = aUp[i].eStart;
pWin->eEnd = aUp[i].eEnd;
pWin->eExclude = 0;
if( pWin->eStart==TK_FOLLOWING ){
pWin->pStart = sqlite3Expr(db, TK_INTEGER, "1");
}
break;
}
}
}
}
pWin->pFunc = pFunc;
}
/*
** Context object passed through sqlite3WalkExprList() to
** selectWindowRewriteExprCb() by selectWindowRewriteEList().
*/
typedef struct WindowRewrite WindowRewrite;
struct WindowRewrite {
Window *pWin;
SrcList *pSrc;
ExprList *pSub;
Table *pTab;
Select *pSubSelect; /* Current sub-select, if any */
};
/*
** Callback function used by selectWindowRewriteEList(). If necessary,
** this function appends to the output expression-list and updates
** expression (*ppExpr) in place.
*/
static int selectWindowRewriteExprCb(Walker *pWalker, Expr *pExpr){
struct WindowRewrite *p = pWalker->u.pRewrite;
Parse *pParse = pWalker->pParse;
assert( p!=0 );
assert( p->pWin!=0 );
/* If this function is being called from within a scalar sub-select
** that used by the SELECT statement being processed, only process
** TK_COLUMN expressions that refer to it (the outer SELECT). Do
** not process aggregates or window functions at all, as they belong
** to the scalar sub-select. */
if( p->pSubSelect ){
if( pExpr->op!=TK_COLUMN ){
return WRC_Continue;
}else{
int nSrc = p->pSrc->nSrc;
int i;
for(i=0; i<nSrc; i++){
if( pExpr->iTable==p->pSrc->a[i].iCursor ) break;
}
if( i==nSrc ) return WRC_Continue;
}
}
switch( pExpr->op ){
case TK_FUNCTION:
if( !ExprHasProperty(pExpr, EP_WinFunc) ){
break;
}else{
Window *pWin;
for(pWin=p->pWin; pWin; pWin=pWin->pNextWin){
if( pExpr->y.pWin==pWin ){
assert( pWin->pOwner==pExpr );
return WRC_Prune;
}
}
}
/* Fall through. */
case TK_AGG_FUNCTION:
case TK_COLUMN: {
Expr *pDup = sqlite3ExprDup(pParse->db, pExpr, 0);
p->pSub = sqlite3ExprListAppend(pParse, p->pSub, pDup);
if( p->pSub ){
assert( ExprHasProperty(pExpr, EP_Static)==0 );
ExprSetProperty(pExpr, EP_Static);
sqlite3ExprDelete(pParse->db, pExpr);
ExprClearProperty(pExpr, EP_Static);
memset(pExpr, 0, sizeof(Expr));
pExpr->op = TK_COLUMN;
pExpr->iColumn = p->pSub->nExpr-1;
pExpr->iTable = p->pWin->iEphCsr;
pExpr->y.pTab = p->pTab;
}
break;
}
default: /* no-op */
break;
}
return WRC_Continue;
}
static int selectWindowRewriteSelectCb(Walker *pWalker, Select *pSelect){
struct WindowRewrite *p = pWalker->u.pRewrite;
Select *pSave = p->pSubSelect;
if( pSave==pSelect ){
return WRC_Continue;
}else{
p->pSubSelect = pSelect;
sqlite3WalkSelect(pWalker, pSelect);
p->pSubSelect = pSave;
}
return WRC_Prune;
}
/*
** Iterate through each expression in expression-list pEList. For each:
**
** * TK_COLUMN,
** * aggregate function, or
** * window function with a Window object that is not a member of the
** Window list passed as the second argument (pWin).
**
** Append the node to output expression-list (*ppSub). And replace it
** with a TK_COLUMN that reads the (N-1)th element of table
** pWin->iEphCsr, where N is the number of elements in (*ppSub) after
** appending the new one.
*/
static void selectWindowRewriteEList(
Parse *pParse,
Window *pWin,
SrcList *pSrc,
ExprList *pEList, /* Rewrite expressions in this list */
Table *pTab,
ExprList **ppSub /* IN/OUT: Sub-select expression-list */
){
Walker sWalker;
WindowRewrite sRewrite;
assert( pWin!=0 );
memset(&sWalker, 0, sizeof(Walker));
memset(&sRewrite, 0, sizeof(WindowRewrite));
sRewrite.pSub = *ppSub;
sRewrite.pWin = pWin;
sRewrite.pSrc = pSrc;
sRewrite.pTab = pTab;
sWalker.pParse = pParse;
sWalker.xExprCallback = selectWindowRewriteExprCb;
sWalker.xSelectCallback = selectWindowRewriteSelectCb;
sWalker.u.pRewrite = &sRewrite;
(void)sqlite3WalkExprList(&sWalker, pEList);
*ppSub = sRewrite.pSub;
}
/*
** Append a copy of each expression in expression-list pAppend to
** expression list pList. Return a pointer to the result list.
*/
static ExprList *exprListAppendList(
Parse *pParse, /* Parsing context */
ExprList *pList, /* List to which to append. Might be NULL */
ExprList *pAppend, /* List of values to append. Might be NULL */
int bIntToNull
){
if( pAppend ){
int i;
int nInit = pList ? pList->nExpr : 0;
for(i=0; i<pAppend->nExpr; i++){
Expr *pDup = sqlite3ExprDup(pParse->db, pAppend->a[i].pExpr, 0);
if( bIntToNull && pDup && pDup->op==TK_INTEGER ){
pDup->op = TK_NULL;
pDup->flags &= ~(EP_IntValue|EP_IsTrue|EP_IsFalse);
}
pList = sqlite3ExprListAppend(pParse, pList, pDup);
if( pList ) pList->a[nInit+i].sortFlags = pAppend->a[i].sortFlags;
}
}
return pList;
}
/*
** If the SELECT statement passed as the second argument does not invoke
** any SQL window functions, this function is a no-op. Otherwise, it
** rewrites the SELECT statement so that window function xStep functions
** are invoked in the correct order as described under "SELECT REWRITING"
** at the top of this file.
*/
int sqlite3WindowRewrite(Parse *pParse, Select *p){
int rc = SQLITE_OK;
if( p->pWin && p->pPrior==0 ){
Vdbe *v = sqlite3GetVdbe(pParse);
sqlite3 *db = pParse->db;
Select *pSub = 0; /* The subquery */
SrcList *pSrc = p->pSrc;
Expr *pWhere = p->pWhere;
ExprList *pGroupBy = p->pGroupBy;
Expr *pHaving = p->pHaving;
ExprList *pSort = 0;
ExprList *pSublist = 0; /* Expression list for sub-query */
Window *pMWin = p->pWin; /* Master window object */
Window *pWin; /* Window object iterator */
Table *pTab;
pTab = sqlite3DbMallocZero(db, sizeof(Table));
if( pTab==0 ){
return SQLITE_NOMEM;
}
p->pSrc = 0;
p->pWhere = 0;
p->pGroupBy = 0;
p->pHaving = 0;
p->selFlags &= ~SF_Aggregate;
/* Create the ORDER BY clause for the sub-select. This is the concatenation
** of the window PARTITION and ORDER BY clauses. Then, if this makes it
** redundant, remove the ORDER BY from the parent SELECT. */
pSort = sqlite3ExprListDup(db, pMWin->pPartition, 0);
pSort = exprListAppendList(pParse, pSort, pMWin->pOrderBy, 1);
if( pSort && p->pOrderBy && p->pOrderBy->nExpr<=pSort->nExpr ){
int nSave = pSort->nExpr;
pSort->nExpr = p->pOrderBy->nExpr;
if( sqlite3ExprListCompare(pSort, p->pOrderBy, -1)==0 ){
sqlite3ExprListDelete(db, p->pOrderBy);
p->pOrderBy = 0;
}
pSort->nExpr = nSave;
}
/* Assign a cursor number for the ephemeral table used to buffer rows.
** The OpenEphemeral instruction is coded later, after it is known how
** many columns the table will have. */
pMWin->iEphCsr = pParse->nTab++;
pParse->nTab += 3;
selectWindowRewriteEList(pParse, pMWin, pSrc, p->pEList, pTab, &pSublist);
selectWindowRewriteEList(pParse, pMWin, pSrc, p->pOrderBy, pTab, &pSublist);
pMWin->nBufferCol = (pSublist ? pSublist->nExpr : 0);
/* Append the PARTITION BY and ORDER BY expressions to the to the
** sub-select expression list. They are required to figure out where
** boundaries for partitions and sets of peer rows lie. */
pSublist = exprListAppendList(pParse, pSublist, pMWin->pPartition, 0);
pSublist = exprListAppendList(pParse, pSublist, pMWin->pOrderBy, 0);
/* Append the arguments passed to each window function to the
** sub-select expression list. Also allocate two registers for each
** window function - one for the accumulator, another for interim
** results. */
for(pWin=pMWin; pWin; pWin=pWin->pNextWin){
ExprList *pArgs = pWin->pOwner->x.pList;
if( pWin->pFunc->funcFlags & SQLITE_FUNC_SUBTYPE ){
selectWindowRewriteEList(pParse, pMWin, pSrc, pArgs, pTab, &pSublist);
pWin->iArgCol = (pSublist ? pSublist->nExpr : 0);
pWin->bExprArgs = 1;
}else{
pWin->iArgCol = (pSublist ? pSublist->nExpr : 0);
pSublist = exprListAppendList(pParse, pSublist, pArgs, 0);
}
if( pWin->pFilter ){
Expr *pFilter = sqlite3ExprDup(db, pWin->pFilter, 0);
pSublist = sqlite3ExprListAppend(pParse, pSublist, pFilter);
}
pWin->regAccum = ++pParse->nMem;
pWin->regResult = ++pParse->nMem;
sqlite3VdbeAddOp2(v, OP_Null, 0, pWin->regAccum);
}
/* If there is no ORDER BY or PARTITION BY clause, and the window
** function accepts zero arguments, and there are no other columns
** selected (e.g. "SELECT row_number() OVER () FROM t1"), it is possible
** that pSublist is still NULL here. Add a constant expression here to
** keep everything legal in this case.
*/
if( pSublist==0 ){
pSublist = sqlite3ExprListAppend(pParse, 0,
sqlite3Expr(db, TK_INTEGER, "0")
);
}
pSub = sqlite3SelectNew(
pParse, pSublist, pSrc, pWhere, pGroupBy, pHaving, pSort, 0, 0
);
p->pSrc = sqlite3SrcListAppend(pParse, 0, 0, 0);
if( p->pSrc ){
Table *pTab2;
p->pSrc->a[0].pSelect = pSub;
sqlite3SrcListAssignCursors(pParse, p->pSrc);
pSub->selFlags |= SF_Expanded;
pTab2 = sqlite3ResultSetOfSelect(pParse, pSub, SQLITE_AFF_NONE);
if( pTab2==0 ){
rc = SQLITE_NOMEM;
}else{
memcpy(pTab, pTab2, sizeof(Table));
pTab->tabFlags |= TF_Ephemeral;
p->pSrc->a[0].pTab = pTab;
pTab = pTab2;
}
sqlite3VdbeAddOp2(v, OP_OpenEphemeral, pMWin->iEphCsr, pSublist->nExpr);
sqlite3VdbeAddOp2(v, OP_OpenDup, pMWin->iEphCsr+1, pMWin->iEphCsr);
sqlite3VdbeAddOp2(v, OP_OpenDup, pMWin->iEphCsr+2, pMWin->iEphCsr);
sqlite3VdbeAddOp2(v, OP_OpenDup, pMWin->iEphCsr+3, pMWin->iEphCsr);
}else{
sqlite3SelectDelete(db, pSub);
}
if( db->mallocFailed ) rc = SQLITE_NOMEM;
sqlite3DbFree(db, pTab);
}
return rc;
}
/*
** Unlink the Window object from the Select to which it is attached,
** if it is attached.
*/
void sqlite3WindowUnlinkFromSelect(Window *p){
if( p->ppThis ){
*p->ppThis = p->pNextWin;
if( p->pNextWin ) p->pNextWin->ppThis = p->ppThis;
p->ppThis = 0;
}
}
/*
** Free the Window object passed as the second argument.
*/
void sqlite3WindowDelete(sqlite3 *db, Window *p){
if( p ){
sqlite3WindowUnlinkFromSelect(p);
sqlite3ExprDelete(db, p->pFilter);
sqlite3ExprListDelete(db, p->pPartition);
sqlite3ExprListDelete(db, p->pOrderBy);
sqlite3ExprDelete(db, p->pEnd);
sqlite3ExprDelete(db, p->pStart);
sqlite3DbFree(db, p->zName);
sqlite3DbFree(db, p->zBase);
sqlite3DbFree(db, p);
}
}
/*
** Free the linked list of Window objects starting at the second argument.
*/
void sqlite3WindowListDelete(sqlite3 *db, Window *p){
while( p ){
Window *pNext = p->pNextWin;
sqlite3WindowDelete(db, p);
p = pNext;
}
}
/*
** The argument expression is an PRECEDING or FOLLOWING offset. The
** value should be a non-negative integer. If the value is not a
** constant, change it to NULL. The fact that it is then a non-negative
** integer will be caught later. But it is important not to leave
** variable values in the expression tree.
*/
static Expr *sqlite3WindowOffsetExpr(Parse *pParse, Expr *pExpr){
if( 0==sqlite3ExprIsConstant(pExpr) ){
if( IN_RENAME_OBJECT ) sqlite3RenameExprUnmap(pParse, pExpr);
sqlite3ExprDelete(pParse->db, pExpr);
pExpr = sqlite3ExprAlloc(pParse->db, TK_NULL, 0, 0);
}
return pExpr;
}
/*
** Allocate and return a new Window object describing a Window Definition.
*/
Window *sqlite3WindowAlloc(
Parse *pParse, /* Parsing context */
int eType, /* Frame type. TK_RANGE, TK_ROWS, TK_GROUPS, or 0 */
int eStart, /* Start type: CURRENT, PRECEDING, FOLLOWING, UNBOUNDED */
Expr *pStart, /* Start window size if TK_PRECEDING or FOLLOWING */
int eEnd, /* End type: CURRENT, FOLLOWING, TK_UNBOUNDED, PRECEDING */
Expr *pEnd, /* End window size if TK_FOLLOWING or PRECEDING */
u8 eExclude /* EXCLUDE clause */
){
Window *pWin = 0;
int bImplicitFrame = 0;
/* Parser assures the following: */
assert( eType==0 || eType==TK_RANGE || eType==TK_ROWS || eType==TK_GROUPS );
assert( eStart==TK_CURRENT || eStart==TK_PRECEDING
|| eStart==TK_UNBOUNDED || eStart==TK_FOLLOWING );
assert( eEnd==TK_CURRENT || eEnd==TK_FOLLOWING
|| eEnd==TK_UNBOUNDED || eEnd==TK_PRECEDING );
assert( (eStart==TK_PRECEDING || eStart==TK_FOLLOWING)==(pStart!=0) );
assert( (eEnd==TK_FOLLOWING || eEnd==TK_PRECEDING)==(pEnd!=0) );
if( eType==0 ){
bImplicitFrame = 1;
eType = TK_RANGE;
}
/* Additionally, the
** starting boundary type may not occur earlier in the following list than
** the ending boundary type:
**
** UNBOUNDED PRECEDING
** <expr> PRECEDING
** CURRENT ROW
** <expr> FOLLOWING
** UNBOUNDED FOLLOWING
**
** The parser ensures that "UNBOUNDED PRECEDING" cannot be used as an ending
** boundary, and than "UNBOUNDED FOLLOWING" cannot be used as a starting
** frame boundary.
*/
if( (eStart==TK_CURRENT && eEnd==TK_PRECEDING)
|| (eStart==TK_FOLLOWING && (eEnd==TK_PRECEDING || eEnd==TK_CURRENT))
){
sqlite3ErrorMsg(pParse, "unsupported frame specification");
goto windowAllocErr;
}
pWin = (Window*)sqlite3DbMallocZero(pParse->db, sizeof(Window));
if( pWin==0 ) goto windowAllocErr;
pWin->eFrmType = eType;
pWin->eStart = eStart;
pWin->eEnd = eEnd;
if( eExclude==0 && OptimizationDisabled(pParse->db, SQLITE_WindowFunc) ){
eExclude = TK_NO;
}
pWin->eExclude = eExclude;
pWin->bImplicitFrame = bImplicitFrame;
pWin->pEnd = sqlite3WindowOffsetExpr(pParse, pEnd);
pWin->pStart = sqlite3WindowOffsetExpr(pParse, pStart);
return pWin;
windowAllocErr:
sqlite3ExprDelete(pParse->db, pEnd);
sqlite3ExprDelete(pParse->db, pStart);
return 0;
}
/*
** Attach PARTITION and ORDER BY clauses pPartition and pOrderBy to window
** pWin. Also, if parameter pBase is not NULL, set pWin->zBase to the
** equivalent nul-terminated string.
*/
Window *sqlite3WindowAssemble(
Parse *pParse,
Window *pWin,
ExprList *pPartition,
ExprList *pOrderBy,
Token *pBase
){
if( pWin ){
pWin->pPartition = pPartition;
pWin->pOrderBy = pOrderBy;
if( pBase ){
pWin->zBase = sqlite3DbStrNDup(pParse->db, pBase->z, pBase->n);
}
}else{
sqlite3ExprListDelete(pParse->db, pPartition);
sqlite3ExprListDelete(pParse->db, pOrderBy);
}
return pWin;
}
/*
** Window *pWin has just been created from a WINDOW clause. Tokne pBase
** is the base window. Earlier windows from the same WINDOW clause are
** stored in the linked list starting at pWin->pNextWin. This function
** either updates *pWin according to the base specification, or else
** leaves an error in pParse.
*/
void sqlite3WindowChain(Parse *pParse, Window *pWin, Window *pList){
if( pWin->zBase ){
sqlite3 *db = pParse->db;
Window *pExist = windowFind(pParse, pList, pWin->zBase);
if( pExist ){
const char *zErr = 0;
/* Check for errors */
if( pWin->pPartition ){
zErr = "PARTITION clause";
}else if( pExist->pOrderBy && pWin->pOrderBy ){
zErr = "ORDER BY clause";
}else if( pExist->bImplicitFrame==0 ){
zErr = "frame specification";
}
if( zErr ){
sqlite3ErrorMsg(pParse,
"cannot override %s of window: %s", zErr, pWin->zBase
);
}else{
pWin->pPartition = sqlite3ExprListDup(db, pExist->pPartition, 0);
if( pExist->pOrderBy ){
assert( pWin->pOrderBy==0 );
pWin->pOrderBy = sqlite3ExprListDup(db, pExist->pOrderBy, 0);
}
sqlite3DbFree(db, pWin->zBase);
pWin->zBase = 0;
}
}
}
}
/*
** Attach window object pWin to expression p.
*/
void sqlite3WindowAttach(Parse *pParse, Expr *p, Window *pWin){
if( p ){
assert( p->op==TK_FUNCTION );
assert( pWin );
p->y.pWin = pWin;
ExprSetProperty(p, EP_WinFunc);
pWin->pOwner = p;
if( (p->flags & EP_Distinct) && pWin->eFrmType!=TK_FILTER ){
sqlite3ErrorMsg(pParse,
"DISTINCT is not supported for window functions"
);
}
}else{
sqlite3WindowDelete(pParse->db, pWin);
}
}
/*
** Possibly link window pWin into the list at pSel->pWin (window functions
** to be processed as part of SELECT statement pSel). The window is linked
** in if either (a) there are no other windows already linked to this
** SELECT, or (b) the windows already linked use a compatible window frame.
*/
void sqlite3WindowLink(Select *pSel, Window *pWin){
if( 0==pSel->pWin
|| 0==sqlite3WindowCompare(0, pSel->pWin, pWin, 0)
){
pWin->pNextWin = pSel->pWin;
if( pSel->pWin ){
pSel->pWin->ppThis = &pWin->pNextWin;
}
pSel->pWin = pWin;
pWin->ppThis = &pSel->pWin;
}
}
/*
** Return 0 if the two window objects are identical, or non-zero otherwise.
** Identical window objects can be processed in a single scan.
*/
int sqlite3WindowCompare(Parse *pParse, Window *p1, Window *p2, int bFilter){
if( p1->eFrmType!=p2->eFrmType ) return 1;
if( p1->eStart!=p2->eStart ) return 1;
if( p1->eEnd!=p2->eEnd ) return 1;
if( p1->eExclude!=p2->eExclude ) return 1;
if( sqlite3ExprCompare(pParse, p1->pStart, p2->pStart, -1) ) return 1;
if( sqlite3ExprCompare(pParse, p1->pEnd, p2->pEnd, -1) ) return 1;
if( sqlite3ExprListCompare(p1->pPartition, p2->pPartition, -1) ) return 1;
if( sqlite3ExprListCompare(p1->pOrderBy, p2->pOrderBy, -1) ) return 1;
if( bFilter ){
if( sqlite3ExprCompare(pParse, p1->pFilter, p2->pFilter, -1) ) return 1;
}
return 0;
}
/*
** This is called by code in select.c before it calls sqlite3WhereBegin()
** to begin iterating through the sub-query results. It is used to allocate
** and initialize registers and cursors used by sqlite3WindowCodeStep().
*/
void sqlite3WindowCodeInit(Parse *pParse, Window *pMWin){
Window *pWin;
Vdbe *v = sqlite3GetVdbe(pParse);
/* Allocate registers to use for PARTITION BY values, if any. Initialize
** said registers to NULL. */
if( pMWin->pPartition ){
int nExpr = pMWin->pPartition->nExpr;
pMWin->regPart = pParse->nMem+1;
pParse->nMem += nExpr;
sqlite3VdbeAddOp3(v, OP_Null, 0, pMWin->regPart, pMWin->regPart+nExpr-1);
}
pMWin->regOne = ++pParse->nMem;
sqlite3VdbeAddOp2(v, OP_Integer, 1, pMWin->regOne);
if( pMWin->eExclude ){
pMWin->regStartRowid = ++pParse->nMem;
pMWin->regEndRowid = ++pParse->nMem;
pMWin->csrApp = pParse->nTab++;
sqlite3VdbeAddOp2(v, OP_Integer, 1, pMWin->regStartRowid);
sqlite3VdbeAddOp2(v, OP_Integer, 0, pMWin->regEndRowid);
sqlite3VdbeAddOp2(v, OP_OpenDup, pMWin->csrApp, pMWin->iEphCsr);
return;
}
for(pWin=pMWin; pWin; pWin=pWin->pNextWin){
FuncDef *p = pWin->pFunc;
if( (p->funcFlags & SQLITE_FUNC_MINMAX) && pWin->eStart!=TK_UNBOUNDED ){
/* The inline versions of min() and max() require a single ephemeral
** table and 3 registers. The registers are used as follows:
**
** regApp+0: slot to copy min()/max() argument to for MakeRecord
** regApp+1: integer value used to ensure keys are unique
** regApp+2: output of MakeRecord
*/
ExprList *pList = pWin->pOwner->x.pList;
KeyInfo *pKeyInfo = sqlite3KeyInfoFromExprList(pParse, pList, 0, 0);
pWin->csrApp = pParse->nTab++;
pWin->regApp = pParse->nMem+1;
pParse->nMem += 3;
if( pKeyInfo && pWin->pFunc->zName[1]=='i' ){
assert( pKeyInfo->aSortFlags[0]==0 );
pKeyInfo->aSortFlags[0] = KEYINFO_ORDER_DESC;
}
sqlite3VdbeAddOp2(v, OP_OpenEphemeral, pWin->csrApp, 2);
sqlite3VdbeAppendP4(v, pKeyInfo, P4_KEYINFO);
sqlite3VdbeAddOp2(v, OP_Integer, 0, pWin->regApp+1);
}
else if( p->zName==nth_valueName || p->zName==first_valueName ){
/* Allocate two registers at pWin->regApp. These will be used to
** store the start and end index of the current frame. */
pWin->regApp = pParse->nMem+1;
pWin->csrApp = pParse->nTab++;
pParse->nMem += 2;
sqlite3VdbeAddOp2(v, OP_OpenDup, pWin->csrApp, pMWin->iEphCsr);
}
else if( p->zName==leadName || p->zName==lagName ){
pWin->csrApp = pParse->nTab++;
sqlite3VdbeAddOp2(v, OP_OpenDup, pWin->csrApp, pMWin->iEphCsr);
}
}
}
#define WINDOW_STARTING_INT 0
#define WINDOW_ENDING_INT 1
#define WINDOW_NTH_VALUE_INT 2
#define WINDOW_STARTING_NUM 3
#define WINDOW_ENDING_NUM 4
/*
** A "PRECEDING <expr>" (eCond==0) or "FOLLOWING <expr>" (eCond==1) or the
** value of the second argument to nth_value() (eCond==2) has just been
** evaluated and the result left in register reg. This function generates VM
** code to check that the value is a non-negative integer and throws an
** exception if it is not.
*/
static void windowCheckValue(Parse *pParse, int reg, int eCond){
static const char *azErr[] = {
"frame starting offset must be a non-negative integer",
"frame ending offset must be a non-negative integer",
"second argument to nth_value must be a positive integer",
"frame starting offset must be a non-negative number",
"frame ending offset must be a non-negative number",
};
static int aOp[] = { OP_Ge, OP_Ge, OP_Gt, OP_Ge, OP_Ge };
Vdbe *v = sqlite3GetVdbe(pParse);
int regZero = sqlite3GetTempReg(pParse);
assert( eCond>=0 && eCond<ArraySize(azErr) );
sqlite3VdbeAddOp2(v, OP_Integer, 0, regZero);
if( eCond>=WINDOW_STARTING_NUM ){
int regString = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp4(v, OP_String8, 0, regString, 0, "", P4_STATIC);
sqlite3VdbeAddOp3(v, OP_Ge, regString, sqlite3VdbeCurrentAddr(v)+2, reg);
sqlite3VdbeChangeP5(v, SQLITE_AFF_NUMERIC|SQLITE_JUMPIFNULL);
VdbeCoverage(v);
assert( eCond==3 || eCond==4 );
VdbeCoverageIf(v, eCond==3);
VdbeCoverageIf(v, eCond==4);
}else{
sqlite3VdbeAddOp2(v, OP_MustBeInt, reg, sqlite3VdbeCurrentAddr(v)+2);
VdbeCoverage(v);
assert( eCond==0 || eCond==1 || eCond==2 );
VdbeCoverageIf(v, eCond==0);
VdbeCoverageIf(v, eCond==1);
VdbeCoverageIf(v, eCond==2);
}
sqlite3VdbeAddOp3(v, aOp[eCond], regZero, sqlite3VdbeCurrentAddr(v)+2, reg);
VdbeCoverageNeverNullIf(v, eCond==0); /* NULL case captured by */
VdbeCoverageNeverNullIf(v, eCond==1); /* the OP_MustBeInt */
VdbeCoverageNeverNullIf(v, eCond==2);
VdbeCoverageNeverNullIf(v, eCond==3); /* NULL case caught by */
VdbeCoverageNeverNullIf(v, eCond==4); /* the OP_Ge */
sqlite3MayAbort(pParse);
sqlite3VdbeAddOp2(v, OP_Halt, SQLITE_ERROR, OE_Abort);
sqlite3VdbeAppendP4(v, (void*)azErr[eCond], P4_STATIC);
sqlite3ReleaseTempReg(pParse, regZero);
}
/*
** Return the number of arguments passed to the window-function associated
** with the object passed as the only argument to this function.
*/
static int windowArgCount(Window *pWin){
ExprList *pList = pWin->pOwner->x.pList;
return (pList ? pList->nExpr : 0);
}
typedef struct WindowCodeArg WindowCodeArg;
typedef struct WindowCsrAndReg WindowCsrAndReg;
/*
** See comments above struct WindowCodeArg.
*/
struct WindowCsrAndReg {
int csr; /* Cursor number */
int reg; /* First in array of peer values */
};
/*
** A single instance of this structure is allocated on the stack by
** sqlite3WindowCodeStep() and a pointer to it passed to the various helper
** routines. This is to reduce the number of arguments required by each
** helper function.
**
** regArg:
** Each window function requires an accumulator register (just as an
** ordinary aggregate function does). This variable is set to the first
** in an array of accumulator registers - one for each window function
** in the WindowCodeArg.pMWin list.
**
** eDelete:
** The window functions implementation sometimes caches the input rows
** that it processes in a temporary table. If it is not zero, this
** variable indicates when rows may be removed from the temp table (in
** order to reduce memory requirements - it would always be safe just
** to leave them there). Possible values for eDelete are:
**
** WINDOW_RETURN_ROW:
** An input row can be discarded after it is returned to the caller.
**
** WINDOW_AGGINVERSE:
** An input row can be discarded after the window functions xInverse()
** callbacks have been invoked in it.
**
** WINDOW_AGGSTEP:
** An input row can be discarded after the window functions xStep()
** callbacks have been invoked in it.
**
** start,current,end
** Consider a window-frame similar to the following:
**
** (ORDER BY a, b GROUPS BETWEEN 2 PRECEDING AND 2 FOLLOWING)
**
** The windows functions implmentation caches the input rows in a temp
** table, sorted by "a, b" (it actually populates the cache lazily, and
** aggressively removes rows once they are no longer required, but that's
** a mere detail). It keeps three cursors open on the temp table. One
** (current) that points to the next row to return to the query engine
** once its window function values have been calculated. Another (end)
** points to the next row to call the xStep() method of each window function
** on (so that it is 2 groups ahead of current). And a third (start) that
** points to the next row to call the xInverse() method of each window
** function on.
**
** Each cursor (start, current and end) consists of a VDBE cursor
** (WindowCsrAndReg.csr) and an array of registers (starting at
** WindowCodeArg.reg) that always contains a copy of the peer values
** read from the corresponding cursor.
**
** Depending on the window-frame in question, all three cursors may not
** be required. In this case both WindowCodeArg.csr and reg are set to
** 0.
*/
struct WindowCodeArg {
Parse *pParse; /* Parse context */
Window *pMWin; /* First in list of functions being processed */
Vdbe *pVdbe; /* VDBE object */
int addrGosub; /* OP_Gosub to this address to return one row */
int regGosub; /* Register used with OP_Gosub(addrGosub) */
int regArg; /* First in array of accumulator registers */
int eDelete; /* See above */
WindowCsrAndReg start;
WindowCsrAndReg current;
WindowCsrAndReg end;
};
/*
** Generate VM code to read the window frames peer values from cursor csr into
** an array of registers starting at reg.
*/
static void windowReadPeerValues(
WindowCodeArg *p,
int csr,
int reg
){
Window *pMWin = p->pMWin;
ExprList *pOrderBy = pMWin->pOrderBy;
if( pOrderBy ){
Vdbe *v = sqlite3GetVdbe(p->pParse);
ExprList *pPart = pMWin->pPartition;
int iColOff = pMWin->nBufferCol + (pPart ? pPart->nExpr : 0);
int i;
for(i=0; i<pOrderBy->nExpr; i++){
sqlite3VdbeAddOp3(v, OP_Column, csr, iColOff+i, reg+i);
}
}
}
/*
** Generate VM code to invoke either xStep() (if bInverse is 0) or
** xInverse (if bInverse is non-zero) for each window function in the
** linked list starting at pMWin. Or, for built-in window functions
** that do not use the standard function API, generate the required
** inline VM code.
**
** If argument csr is greater than or equal to 0, then argument reg is
** the first register in an array of registers guaranteed to be large
** enough to hold the array of arguments for each function. In this case
** the arguments are extracted from the current row of csr into the
** array of registers before invoking OP_AggStep or OP_AggInverse
**
** Or, if csr is less than zero, then the array of registers at reg is
** already populated with all columns from the current row of the sub-query.
**
** If argument regPartSize is non-zero, then it is a register containing the
** number of rows in the current partition.
*/
static void windowAggStep(
WindowCodeArg *p,
Window *pMWin, /* Linked list of window functions */
int csr, /* Read arguments from this cursor */
int bInverse, /* True to invoke xInverse instead of xStep */
int reg /* Array of registers */
){
Parse *pParse = p->pParse;
Vdbe *v = sqlite3GetVdbe(pParse);
Window *pWin;
for(pWin=pMWin; pWin; pWin=pWin->pNextWin){
FuncDef *pFunc = pWin->pFunc;
int regArg;
int nArg = pWin->bExprArgs ? 0 : windowArgCount(pWin);
int i;
assert( bInverse==0 || pWin->eStart!=TK_UNBOUNDED );
/* All OVER clauses in the same window function aggregate step must
** be the same. */
assert( pWin==pMWin || sqlite3WindowCompare(pParse,pWin,pMWin,0)==0 );
for(i=0; i<nArg; i++){
if( i!=1 || pFunc->zName!=nth_valueName ){
sqlite3VdbeAddOp3(v, OP_Column, csr, pWin->iArgCol+i, reg+i);
}else{
sqlite3VdbeAddOp3(v, OP_Column, pMWin->iEphCsr, pWin->iArgCol+i, reg+i);
}
}
regArg = reg;
if( pMWin->regStartRowid==0
&& (pFunc->funcFlags & SQLITE_FUNC_MINMAX)
&& (pWin->eStart!=TK_UNBOUNDED)
){
int addrIsNull = sqlite3VdbeAddOp1(v, OP_IsNull, regArg);
VdbeCoverage(v);
if( bInverse==0 ){
sqlite3VdbeAddOp2(v, OP_AddImm, pWin->regApp+1, 1);
sqlite3VdbeAddOp2(v, OP_SCopy, regArg, pWin->regApp);
sqlite3VdbeAddOp3(v, OP_MakeRecord, pWin->regApp, 2, pWin->regApp+2);
sqlite3VdbeAddOp2(v, OP_IdxInsert, pWin->csrApp, pWin->regApp+2);
}else{
sqlite3VdbeAddOp4Int(v, OP_SeekGE, pWin->csrApp, 0, regArg, 1);
VdbeCoverageNeverTaken(v);
sqlite3VdbeAddOp1(v, OP_Delete, pWin->csrApp);
sqlite3VdbeJumpHere(v, sqlite3VdbeCurrentAddr(v)-2);
}
sqlite3VdbeJumpHere(v, addrIsNull);
}else if( pWin->regApp ){
assert( pFunc->zName==nth_valueName
|| pFunc->zName==first_valueName
);
assert( bInverse==0 || bInverse==1 );
sqlite3VdbeAddOp2(v, OP_AddImm, pWin->regApp+1-bInverse, 1);
}else if( pFunc->xSFunc!=noopStepFunc ){
int addrIf = 0;
if( pWin->pFilter ){
int regTmp;
assert( pWin->bExprArgs || !nArg ||nArg==pWin->pOwner->x.pList->nExpr );
assert( pWin->bExprArgs || nArg ||pWin->pOwner->x.pList==0 );
regTmp = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp3(v, OP_Column, csr, pWin->iArgCol+nArg,regTmp);
addrIf = sqlite3VdbeAddOp3(v, OP_IfNot, regTmp, 0, 1);
VdbeCoverage(v);
sqlite3ReleaseTempReg(pParse, regTmp);
}
if( pWin->bExprArgs ){
int iStart = sqlite3VdbeCurrentAddr(v);
VdbeOp *pOp, *pEnd;
nArg = pWin->pOwner->x.pList->nExpr;
regArg = sqlite3GetTempRange(pParse, nArg);
sqlite3ExprCodeExprList(pParse, pWin->pOwner->x.pList, regArg, 0, 0);
pEnd = sqlite3VdbeGetOp(v, -1);
for(pOp=sqlite3VdbeGetOp(v, iStart); pOp<=pEnd; pOp++){
if( pOp->opcode==OP_Column && pOp->p1==pWin->iEphCsr ){
pOp->p1 = csr;
}
}
}
if( pFunc->funcFlags & SQLITE_FUNC_NEEDCOLL ){
CollSeq *pColl;
assert( nArg>0 );
pColl = sqlite3ExprNNCollSeq(pParse, pWin->pOwner->x.pList->a[0].pExpr);
sqlite3VdbeAddOp4(v, OP_CollSeq, 0,0,0, (const char*)pColl, P4_COLLSEQ);
}
sqlite3VdbeAddOp3(v, bInverse? OP_AggInverse : OP_AggStep,
bInverse, regArg, pWin->regAccum);
sqlite3VdbeAppendP4(v, pFunc, P4_FUNCDEF);
sqlite3VdbeChangeP5(v, (u8)nArg);
if( pWin->bExprArgs ){
sqlite3ReleaseTempRange(pParse, regArg, nArg);
}
if( addrIf ) sqlite3VdbeJumpHere(v, addrIf);
}
}
}
/*
** Values that may be passed as the second argument to windowCodeOp().
*/
#define WINDOW_RETURN_ROW 1
#define WINDOW_AGGINVERSE 2
#define WINDOW_AGGSTEP 3
/*
** Generate VM code to invoke either xValue() (bFin==0) or xFinalize()
** (bFin==1) for each window function in the linked list starting at
** pMWin. Or, for built-in window-functions that do not use the standard
** API, generate the equivalent VM code.
*/
static void windowAggFinal(WindowCodeArg *p, int bFin){
Parse *pParse = p->pParse;
Window *pMWin = p->pMWin;
Vdbe *v = sqlite3GetVdbe(pParse);
Window *pWin;
for(pWin=pMWin; pWin; pWin=pWin->pNextWin){
if( pMWin->regStartRowid==0
&& (pWin->pFunc->funcFlags & SQLITE_FUNC_MINMAX)
&& (pWin->eStart!=TK_UNBOUNDED)
){
sqlite3VdbeAddOp2(v, OP_Null, 0, pWin->regResult);
sqlite3VdbeAddOp1(v, OP_Last, pWin->csrApp);
VdbeCoverage(v);
sqlite3VdbeAddOp3(v, OP_Column, pWin->csrApp, 0, pWin->regResult);
sqlite3VdbeJumpHere(v, sqlite3VdbeCurrentAddr(v)-2);
}else if( pWin->regApp ){
assert( pMWin->regStartRowid==0 );
}else{
int nArg = windowArgCount(pWin);
if( bFin ){
sqlite3VdbeAddOp2(v, OP_AggFinal, pWin->regAccum, nArg);
sqlite3VdbeAppendP4(v, pWin->pFunc, P4_FUNCDEF);
sqlite3VdbeAddOp2(v, OP_Copy, pWin->regAccum, pWin->regResult);
sqlite3VdbeAddOp2(v, OP_Null, 0, pWin->regAccum);
}else{
sqlite3VdbeAddOp3(v, OP_AggValue,pWin->regAccum,nArg,pWin->regResult);
sqlite3VdbeAppendP4(v, pWin->pFunc, P4_FUNCDEF);
}
}
}
}
/*
** Generate code to calculate the current values of all window functions in the
** p->pMWin list by doing a full scan of the current window frame. Store the
** results in the Window.regResult registers, ready to return the upper
** layer.
*/
static void windowFullScan(WindowCodeArg *p){
Window *pWin;
Parse *pParse = p->pParse;
Window *pMWin = p->pMWin;
Vdbe *v = p->pVdbe;
int regCRowid = 0; /* Current rowid value */
int regCPeer = 0; /* Current peer values */
int regRowid = 0; /* AggStep rowid value */
int regPeer = 0; /* AggStep peer values */
int nPeer;
int lblNext;
int lblBrk;
int addrNext;
int csr;
VdbeModuleComment((v, "windowFullScan begin"));
assert( pMWin!=0 );
csr = pMWin->csrApp;
nPeer = (pMWin->pOrderBy ? pMWin->pOrderBy->nExpr : 0);
lblNext = sqlite3VdbeMakeLabel(pParse);
lblBrk = sqlite3VdbeMakeLabel(pParse);
regCRowid = sqlite3GetTempReg(pParse);
regRowid = sqlite3GetTempReg(pParse);
if( nPeer ){
regCPeer = sqlite3GetTempRange(pParse, nPeer);
regPeer = sqlite3GetTempRange(pParse, nPeer);
}
sqlite3VdbeAddOp2(v, OP_Rowid, pMWin->iEphCsr, regCRowid);
windowReadPeerValues(p, pMWin->iEphCsr, regCPeer);
for(pWin=pMWin; pWin; pWin=pWin->pNextWin){
sqlite3VdbeAddOp2(v, OP_Null, 0, pWin->regAccum);
}
sqlite3VdbeAddOp3(v, OP_SeekGE, csr, lblBrk, pMWin->regStartRowid);
VdbeCoverage(v);
addrNext = sqlite3VdbeCurrentAddr(v);
sqlite3VdbeAddOp2(v, OP_Rowid, csr, regRowid);
sqlite3VdbeAddOp3(v, OP_Gt, pMWin->regEndRowid, lblBrk, regRowid);
VdbeCoverageNeverNull(v);
if( pMWin->eExclude==TK_CURRENT ){
sqlite3VdbeAddOp3(v, OP_Eq, regCRowid, lblNext, regRowid);
VdbeCoverageNeverNull(v);
}else if( pMWin->eExclude!=TK_NO ){
int addr;
int addrEq = 0;
KeyInfo *pKeyInfo = 0;
if( pMWin->pOrderBy ){
pKeyInfo = sqlite3KeyInfoFromExprList(pParse, pMWin->pOrderBy, 0, 0);
}
if( pMWin->eExclude==TK_TIES ){
addrEq = sqlite3VdbeAddOp3(v, OP_Eq, regCRowid, 0, regRowid);
VdbeCoverageNeverNull(v);
}
if( pKeyInfo ){
windowReadPeerValues(p, csr, regPeer);
sqlite3VdbeAddOp3(v, OP_Compare, regPeer, regCPeer, nPeer);
sqlite3VdbeAppendP4(v, (void*)pKeyInfo, P4_KEYINFO);
addr = sqlite3VdbeCurrentAddr(v)+1;
sqlite3VdbeAddOp3(v, OP_Jump, addr, lblNext, addr);
VdbeCoverageEqNe(v);
}else{
sqlite3VdbeAddOp2(v, OP_Goto, 0, lblNext);
}
if( addrEq ) sqlite3VdbeJumpHere(v, addrEq);
}
windowAggStep(p, pMWin, csr, 0, p->regArg);
sqlite3VdbeResolveLabel(v, lblNext);
sqlite3VdbeAddOp2(v, OP_Next, csr, addrNext);
VdbeCoverage(v);
sqlite3VdbeJumpHere(v, addrNext-1);
sqlite3VdbeJumpHere(v, addrNext+1);
sqlite3ReleaseTempReg(pParse, regRowid);
sqlite3ReleaseTempReg(pParse, regCRowid);
if( nPeer ){
sqlite3ReleaseTempRange(pParse, regPeer, nPeer);
sqlite3ReleaseTempRange(pParse, regCPeer, nPeer);
}
windowAggFinal(p, 1);
VdbeModuleComment((v, "windowFullScan end"));
}
/*
** Invoke the sub-routine at regGosub (generated by code in select.c) to
** return the current row of Window.iEphCsr. If all window functions are
** aggregate window functions that use the standard API, a single
** OP_Gosub instruction is all that this routine generates. Extra VM code
** for per-row processing is only generated for the following built-in window
** functions:
**
** nth_value()
** first_value()
** lag()
** lead()
*/
static void windowReturnOneRow(WindowCodeArg *p){
Window *pMWin = p->pMWin;
Vdbe *v = p->pVdbe;
if( pMWin->regStartRowid ){
windowFullScan(p);
}else{
Parse *pParse = p->pParse;
Window *pWin;
for(pWin=pMWin; pWin; pWin=pWin->pNextWin){
FuncDef *pFunc = pWin->pFunc;
if( pFunc->zName==nth_valueName
|| pFunc->zName==first_valueName
){
int csr = pWin->csrApp;
int lbl = sqlite3VdbeMakeLabel(pParse);
int tmpReg = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp2(v, OP_Null, 0, pWin->regResult);
if( pFunc->zName==nth_valueName ){
sqlite3VdbeAddOp3(v, OP_Column,pMWin->iEphCsr,pWin->iArgCol+1,tmpReg);
windowCheckValue(pParse, tmpReg, 2);
}else{
sqlite3VdbeAddOp2(v, OP_Integer, 1, tmpReg);
}
sqlite3VdbeAddOp3(v, OP_Add, tmpReg, pWin->regApp, tmpReg);
sqlite3VdbeAddOp3(v, OP_Gt, pWin->regApp+1, lbl, tmpReg);
VdbeCoverageNeverNull(v);
sqlite3VdbeAddOp3(v, OP_SeekRowid, csr, 0, tmpReg);
VdbeCoverageNeverTaken(v);
sqlite3VdbeAddOp3(v, OP_Column, csr, pWin->iArgCol, pWin->regResult);
sqlite3VdbeResolveLabel(v, lbl);
sqlite3ReleaseTempReg(pParse, tmpReg);
}
else if( pFunc->zName==leadName || pFunc->zName==lagName ){
int nArg = pWin->pOwner->x.pList->nExpr;
int csr = pWin->csrApp;
int lbl = sqlite3VdbeMakeLabel(pParse);
int tmpReg = sqlite3GetTempReg(pParse);
int iEph = pMWin->iEphCsr;
if( nArg<3 ){
sqlite3VdbeAddOp2(v, OP_Null, 0, pWin->regResult);
}else{
sqlite3VdbeAddOp3(v, OP_Column, iEph,pWin->iArgCol+2,pWin->regResult);
}
sqlite3VdbeAddOp2(v, OP_Rowid, iEph, tmpReg);
if( nArg<2 ){
int val = (pFunc->zName==leadName ? 1 : -1);
sqlite3VdbeAddOp2(v, OP_AddImm, tmpReg, val);
}else{
int op = (pFunc->zName==leadName ? OP_Add : OP_Subtract);
int tmpReg2 = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp3(v, OP_Column, iEph, pWin->iArgCol+1, tmpReg2);
sqlite3VdbeAddOp3(v, op, tmpReg2, tmpReg, tmpReg);
sqlite3ReleaseTempReg(pParse, tmpReg2);
}
sqlite3VdbeAddOp3(v, OP_SeekRowid, csr, lbl, tmpReg);
VdbeCoverage(v);
sqlite3VdbeAddOp3(v, OP_Column, csr, pWin->iArgCol, pWin->regResult);
sqlite3VdbeResolveLabel(v, lbl);
sqlite3ReleaseTempReg(pParse, tmpReg);
}
}
}
sqlite3VdbeAddOp2(v, OP_Gosub, p->regGosub, p->addrGosub);
}
/*
** Generate code to set the accumulator register for each window function
** in the linked list passed as the second argument to NULL. And perform
** any equivalent initialization required by any built-in window functions
** in the list.
*/
static int windowInitAccum(Parse *pParse, Window *pMWin){
Vdbe *v = sqlite3GetVdbe(pParse);
int regArg;
int nArg = 0;
Window *pWin;
for(pWin=pMWin; pWin; pWin=pWin->pNextWin){
FuncDef *pFunc = pWin->pFunc;
sqlite3VdbeAddOp2(v, OP_Null, 0, pWin->regAccum);
nArg = MAX(nArg, windowArgCount(pWin));
if( pMWin->regStartRowid==0 ){
if( pFunc->zName==nth_valueName || pFunc->zName==first_valueName ){
sqlite3VdbeAddOp2(v, OP_Integer, 0, pWin->regApp);
sqlite3VdbeAddOp2(v, OP_Integer, 0, pWin->regApp+1);
}
if( (pFunc->funcFlags & SQLITE_FUNC_MINMAX) && pWin->csrApp ){
assert( pWin->eStart!=TK_UNBOUNDED );
sqlite3VdbeAddOp1(v, OP_ResetSorter, pWin->csrApp);
sqlite3VdbeAddOp2(v, OP_Integer, 0, pWin->regApp+1);
}
}
}
regArg = pParse->nMem+1;
pParse->nMem += nArg;
return regArg;
}
/*
** Return true if the current frame should be cached in the ephemeral table,
** even if there are no xInverse() calls required.
*/
static int windowCacheFrame(Window *pMWin){
Window *pWin;
if( pMWin->regStartRowid ) return 1;
for(pWin=pMWin; pWin; pWin=pWin->pNextWin){
FuncDef *pFunc = pWin->pFunc;
if( (pFunc->zName==nth_valueName)
|| (pFunc->zName==first_valueName)
|| (pFunc->zName==leadName)
|| (pFunc->zName==lagName)
){
return 1;
}
}
return 0;
}
/*
** regOld and regNew are each the first register in an array of size
** pOrderBy->nExpr. This function generates code to compare the two
** arrays of registers using the collation sequences and other comparison
** parameters specified by pOrderBy.
**
** If the two arrays are not equal, the contents of regNew is copied to
** regOld and control falls through. Otherwise, if the contents of the arrays
** are equal, an OP_Goto is executed. The address of the OP_Goto is returned.
*/
static void windowIfNewPeer(
Parse *pParse,
ExprList *pOrderBy,
int regNew, /* First in array of new values */
int regOld, /* First in array of old values */
int addr /* Jump here */
){
Vdbe *v = sqlite3GetVdbe(pParse);
if( pOrderBy ){
int nVal = pOrderBy->nExpr;
KeyInfo *pKeyInfo = sqlite3KeyInfoFromExprList(pParse, pOrderBy, 0, 0);
sqlite3VdbeAddOp3(v, OP_Compare, regOld, regNew, nVal);
sqlite3VdbeAppendP4(v, (void*)pKeyInfo, P4_KEYINFO);
sqlite3VdbeAddOp3(v, OP_Jump,
sqlite3VdbeCurrentAddr(v)+1, addr, sqlite3VdbeCurrentAddr(v)+1
);
VdbeCoverageEqNe(v);
sqlite3VdbeAddOp3(v, OP_Copy, regNew, regOld, nVal-1);
}else{
sqlite3VdbeAddOp2(v, OP_Goto, 0, addr);
}
}
/*
** This function is called as part of generating VM programs for RANGE
** offset PRECEDING/FOLLOWING frame boundaries. Assuming "ASC" order for
** the ORDER BY term in the window, and that argument op is OP_Ge, it generates
** code equivalent to:
**
** if( csr1.peerVal + regVal >= csr2.peerVal ) goto lbl;
**
** The value of parameter op may also be OP_Gt or OP_Le. In these cases the
** operator in the above pseudo-code is replaced with ">" or "<=", respectively.
**
** If the sort-order for the ORDER BY term in the window is DESC, then the
** comparison is reversed. Instead of adding regVal to csr1.peerVal, it is
** subtracted. And the comparison operator is inverted to - ">=" becomes "<=",
** ">" becomes "<", and so on. So, with DESC sort order, if the argument op
** is OP_Ge, the generated code is equivalent to:
**
** if( csr1.peerVal - regVal <= csr2.peerVal ) goto lbl;
**
** A special type of arithmetic is used such that if csr1.peerVal is not
** a numeric type (real or integer), then the result of the addition addition
** or subtraction is a a copy of csr1.peerVal.
*/
static void windowCodeRangeTest(
WindowCodeArg *p,
int op, /* OP_Ge, OP_Gt, or OP_Le */
int csr1, /* Cursor number for cursor 1 */
int regVal, /* Register containing non-negative number */
int csr2, /* Cursor number for cursor 2 */
int lbl /* Jump destination if condition is true */
){
Parse *pParse = p->pParse;
Vdbe *v = sqlite3GetVdbe(pParse);
ExprList *pOrderBy = p->pMWin->pOrderBy; /* ORDER BY clause for window */
int reg1 = sqlite3GetTempReg(pParse); /* Reg. for csr1.peerVal+regVal */
int reg2 = sqlite3GetTempReg(pParse); /* Reg. for csr2.peerVal */
int regString = ++pParse->nMem; /* Reg. for constant value '' */
int arith = OP_Add; /* OP_Add or OP_Subtract */
int addrGe; /* Jump destination */
assert( op==OP_Ge || op==OP_Gt || op==OP_Le );
assert( pOrderBy && pOrderBy->nExpr==1 );
if( pOrderBy->a[0].sortFlags & KEYINFO_ORDER_DESC ){
switch( op ){
case OP_Ge: op = OP_Le; break;
case OP_Gt: op = OP_Lt; break;
default: assert( op==OP_Le ); op = OP_Ge; break;
}
arith = OP_Subtract;
}
/* Read the peer-value from each cursor into a register */
windowReadPeerValues(p, csr1, reg1);
windowReadPeerValues(p, csr2, reg2);
VdbeModuleComment((v, "CodeRangeTest: if( R%d %s R%d %s R%d ) goto lbl",
reg1, (arith==OP_Add ? "+" : "-"), regVal,
((op==OP_Ge) ? ">=" : (op==OP_Le) ? "<=" : (op==OP_Gt) ? ">" : "<"), reg2
));
/* Register reg1 currently contains csr1.peerVal (the peer-value from csr1).
** This block adds (or subtracts for DESC) the numeric value in regVal
** from it. Or, if reg1 is not numeric (it is a NULL, a text value or a blob),
** then leave reg1 as it is. In pseudo-code, this is implemented as:
**
** if( reg1>='' ) goto addrGe;
** reg1 = reg1 +/- regVal
** addrGe:
**
** Since all strings and blobs are greater-than-or-equal-to an empty string,
** the add/subtract is skipped for these, as required. If reg1 is a NULL,
** then the arithmetic is performed, but since adding or subtracting from
** NULL is always NULL anyway, this case is handled as required too. */
sqlite3VdbeAddOp4(v, OP_String8, 0, regString, 0, "", P4_STATIC);
addrGe = sqlite3VdbeAddOp3(v, OP_Ge, regString, 0, reg1);
VdbeCoverage(v);
sqlite3VdbeAddOp3(v, arith, regVal, reg1, reg1);
sqlite3VdbeJumpHere(v, addrGe);
/* If the BIGNULL flag is set for the ORDER BY, then it is required to
** consider NULL values to be larger than all other values, instead of
** the usual smaller. The VDBE opcodes OP_Ge and so on do not handle this
** (and adding that capability causes a performance regression), so
** instead if the BIGNULL flag is set then cases where either reg1 or
** reg2 are NULL are handled separately in the following block. The code
** generated is equivalent to:
**
** if( reg1 IS NULL ){
** if( op==OP_Ge ) goto lbl;
** if( op==OP_Gt && reg2 IS NOT NULL ) goto lbl;
** if( op==OP_Le && reg2 IS NULL ) goto lbl;
** }else if( reg2 IS NULL ){
** if( op==OP_Le ) goto lbl;
** }
**
** Additionally, if either reg1 or reg2 are NULL but the jump to lbl is
** not taken, control jumps over the comparison operator coded below this
** block. */
if( pOrderBy->a[0].sortFlags & KEYINFO_ORDER_BIGNULL ){
/* This block runs if reg1 contains a NULL. */
int addr = sqlite3VdbeAddOp1(v, OP_NotNull, reg1); VdbeCoverage(v);
switch( op ){
case OP_Ge:
sqlite3VdbeAddOp2(v, OP_Goto, 0, lbl);
break;
case OP_Gt:
sqlite3VdbeAddOp2(v, OP_NotNull, reg2, lbl);
VdbeCoverage(v);
break;
case OP_Le:
sqlite3VdbeAddOp2(v, OP_IsNull, reg2, lbl);
VdbeCoverage(v);
break;
default: assert( op==OP_Lt ); /* no-op */ break;
}
sqlite3VdbeAddOp2(v, OP_Goto, 0, sqlite3VdbeCurrentAddr(v)+3);
/* This block runs if reg1 is not NULL, but reg2 is. */
sqlite3VdbeJumpHere(v, addr);
sqlite3VdbeAddOp2(v, OP_IsNull, reg2, lbl); VdbeCoverage(v);
if( op==OP_Gt || op==OP_Ge ){
sqlite3VdbeChangeP2(v, -1, sqlite3VdbeCurrentAddr(v)+1);
}
}
/* Compare registers reg2 and reg1, taking the jump if required. Note that
** control skips over this test if the BIGNULL flag is set and either
** reg1 or reg2 contain a NULL value. */
sqlite3VdbeAddOp3(v, op, reg2, lbl, reg1); VdbeCoverage(v);
sqlite3VdbeChangeP5(v, SQLITE_NULLEQ);
assert( op==OP_Ge || op==OP_Gt || op==OP_Lt || op==OP_Le );
testcase(op==OP_Ge); VdbeCoverageIf(v, op==OP_Ge);
testcase(op==OP_Lt); VdbeCoverageIf(v, op==OP_Lt);
testcase(op==OP_Le); VdbeCoverageIf(v, op==OP_Le);
testcase(op==OP_Gt); VdbeCoverageIf(v, op==OP_Gt);
sqlite3ReleaseTempReg(pParse, reg1);
sqlite3ReleaseTempReg(pParse, reg2);
VdbeModuleComment((v, "CodeRangeTest: end"));
}
/*
** Helper function for sqlite3WindowCodeStep(). Each call to this function
** generates VM code for a single RETURN_ROW, AGGSTEP or AGGINVERSE
** operation. Refer to the header comment for sqlite3WindowCodeStep() for
** details.
*/
static int windowCodeOp(
WindowCodeArg *p, /* Context object */
int op, /* WINDOW_RETURN_ROW, AGGSTEP or AGGINVERSE */
int regCountdown, /* Register for OP_IfPos countdown */
int jumpOnEof /* Jump here if stepped cursor reaches EOF */
){
int csr, reg;
Parse *pParse = p->pParse;
Window *pMWin = p->pMWin;
int ret = 0;
Vdbe *v = p->pVdbe;
int addrContinue = 0;
int bPeer = (pMWin->eFrmType!=TK_ROWS);
int lblDone = sqlite3VdbeMakeLabel(pParse);
int addrNextRange = 0;
/* Special case - WINDOW_AGGINVERSE is always a no-op if the frame
** starts with UNBOUNDED PRECEDING. */
if( op==WINDOW_AGGINVERSE && pMWin->eStart==TK_UNBOUNDED ){
assert( regCountdown==0 && jumpOnEof==0 );
return 0;
}
if( regCountdown>0 ){
if( pMWin->eFrmType==TK_RANGE ){
addrNextRange = sqlite3VdbeCurrentAddr(v);
assert( op==WINDOW_AGGINVERSE || op==WINDOW_AGGSTEP );
if( op==WINDOW_AGGINVERSE ){
if( pMWin->eStart==TK_FOLLOWING ){
windowCodeRangeTest(
p, OP_Le, p->current.csr, regCountdown, p->start.csr, lblDone
);
}else{
windowCodeRangeTest(
p, OP_Ge, p->start.csr, regCountdown, p->current.csr, lblDone
);
}
}else{
windowCodeRangeTest(
p, OP_Gt, p->end.csr, regCountdown, p->current.csr, lblDone
);
}
}else{
sqlite3VdbeAddOp3(v, OP_IfPos, regCountdown, lblDone, 1);
VdbeCoverage(v);
}
}
if( op==WINDOW_RETURN_ROW && pMWin->regStartRowid==0 ){
windowAggFinal(p, 0);
}
addrContinue = sqlite3VdbeCurrentAddr(v);
/* If this is a (RANGE BETWEEN a FOLLOWING AND b FOLLOWING) or
** (RANGE BETWEEN b PRECEDING AND a PRECEDING) frame, ensure the
** start cursor does not advance past the end cursor within the
** temporary table. It otherwise might, if (a>b). */
if( pMWin->eStart==pMWin->eEnd && regCountdown
&& pMWin->eFrmType==TK_RANGE && op==WINDOW_AGGINVERSE
){
int regRowid1 = sqlite3GetTempReg(pParse);
int regRowid2 = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp2(v, OP_Rowid, p->start.csr, regRowid1);
sqlite3VdbeAddOp2(v, OP_Rowid, p->end.csr, regRowid2);
sqlite3VdbeAddOp3(v, OP_Ge, regRowid2, lblDone, regRowid1);
VdbeCoverage(v);
sqlite3ReleaseTempReg(pParse, regRowid1);
sqlite3ReleaseTempReg(pParse, regRowid2);
assert( pMWin->eStart==TK_PRECEDING || pMWin->eStart==TK_FOLLOWING );
}
switch( op ){
case WINDOW_RETURN_ROW:
csr = p->current.csr;
reg = p->current.reg;
windowReturnOneRow(p);
break;
case WINDOW_AGGINVERSE:
csr = p->start.csr;
reg = p->start.reg;
if( pMWin->regStartRowid ){
assert( pMWin->regEndRowid );
sqlite3VdbeAddOp2(v, OP_AddImm, pMWin->regStartRowid, 1);
}else{
windowAggStep(p, pMWin, csr, 1, p->regArg);
}
break;
default:
assert( op==WINDOW_AGGSTEP );
csr = p->end.csr;
reg = p->end.reg;
if( pMWin->regStartRowid ){
assert( pMWin->regEndRowid );
sqlite3VdbeAddOp2(v, OP_AddImm, pMWin->regEndRowid, 1);
}else{
windowAggStep(p, pMWin, csr, 0, p->regArg);
}
break;
}
if( op==p->eDelete ){
sqlite3VdbeAddOp1(v, OP_Delete, csr);
sqlite3VdbeChangeP5(v, OPFLAG_SAVEPOSITION);
}
if( jumpOnEof ){
sqlite3VdbeAddOp2(v, OP_Next, csr, sqlite3VdbeCurrentAddr(v)+2);
VdbeCoverage(v);
ret = sqlite3VdbeAddOp0(v, OP_Goto);
}else{
sqlite3VdbeAddOp2(v, OP_Next, csr, sqlite3VdbeCurrentAddr(v)+1+bPeer);
VdbeCoverage(v);
if( bPeer ){
sqlite3VdbeAddOp2(v, OP_Goto, 0, lblDone);
}
}
if( bPeer ){
int nReg = (pMWin->pOrderBy ? pMWin->pOrderBy->nExpr : 0);
int regTmp = (nReg ? sqlite3GetTempRange(pParse, nReg) : 0);
windowReadPeerValues(p, csr, regTmp);
windowIfNewPeer(pParse, pMWin->pOrderBy, regTmp, reg, addrContinue);
sqlite3ReleaseTempRange(pParse, regTmp, nReg);
}
if( addrNextRange ){
sqlite3VdbeAddOp2(v, OP_Goto, 0, addrNextRange);
}
sqlite3VdbeResolveLabel(v, lblDone);
return ret;
}
/*
** Allocate and return a duplicate of the Window object indicated by the
** third argument. Set the Window.pOwner field of the new object to
** pOwner.
*/
Window *sqlite3WindowDup(sqlite3 *db, Expr *pOwner, Window *p){
Window *pNew = 0;
if( ALWAYS(p) ){
pNew = sqlite3DbMallocZero(db, sizeof(Window));
if( pNew ){
pNew->zName = sqlite3DbStrDup(db, p->zName);
pNew->zBase = sqlite3DbStrDup(db, p->zBase);
pNew->pFilter = sqlite3ExprDup(db, p->pFilter, 0);
pNew->pFunc = p->pFunc;
pNew->pPartition = sqlite3ExprListDup(db, p->pPartition, 0);
pNew->pOrderBy = sqlite3ExprListDup(db, p->pOrderBy, 0);
pNew->eFrmType = p->eFrmType;
pNew->eEnd = p->eEnd;
pNew->eStart = p->eStart;
pNew->eExclude = p->eExclude;
pNew->regResult = p->regResult;
pNew->pStart = sqlite3ExprDup(db, p->pStart, 0);
pNew->pEnd = sqlite3ExprDup(db, p->pEnd, 0);
pNew->pOwner = pOwner;
pNew->bImplicitFrame = p->bImplicitFrame;
}
}
return pNew;
}
/*
** Return a copy of the linked list of Window objects passed as the
** second argument.
*/
Window *sqlite3WindowListDup(sqlite3 *db, Window *p){
Window *pWin;
Window *pRet = 0;
Window **pp = &pRet;
for(pWin=p; pWin; pWin=pWin->pNextWin){
*pp = sqlite3WindowDup(db, 0, pWin);
if( *pp==0 ) break;
pp = &((*pp)->pNextWin);
}
return pRet;
}
/*
** Return true if it can be determined at compile time that expression
** pExpr evaluates to a value that, when cast to an integer, is greater
** than zero. False otherwise.
**
** If an OOM error occurs, this function sets the Parse.db.mallocFailed
** flag and returns zero.
*/
static int windowExprGtZero(Parse *pParse, Expr *pExpr){
int ret = 0;
sqlite3 *db = pParse->db;
sqlite3_value *pVal = 0;
sqlite3ValueFromExpr(db, pExpr, db->enc, SQLITE_AFF_NUMERIC, &pVal);
if( pVal && sqlite3_value_int(pVal)>0 ){
ret = 1;
}
sqlite3ValueFree(pVal);
return ret;
}
/*
** sqlite3WhereBegin() has already been called for the SELECT statement
** passed as the second argument when this function is invoked. It generates
** code to populate the Window.regResult register for each window function
** and invoke the sub-routine at instruction addrGosub once for each row.
** sqlite3WhereEnd() is always called before returning.
**
** This function handles several different types of window frames, which
** require slightly different processing. The following pseudo code is
** used to implement window frames of the form:
**
** ROWS BETWEEN <expr1> PRECEDING AND <expr2> FOLLOWING
**
** Other window frame types use variants of the following:
**
** ... loop started by sqlite3WhereBegin() ...
** if( new partition ){
** Gosub flush
** }
** Insert new row into eph table.
**
** if( first row of partition ){
** // Rewind three cursors, all open on the eph table.
** Rewind(csrEnd);
** Rewind(csrStart);
** Rewind(csrCurrent);
**
** regEnd = <expr2> // FOLLOWING expression
** regStart = <expr1> // PRECEDING expression
** }else{
** // First time this branch is taken, the eph table contains two
** // rows. The first row in the partition, which all three cursors
** // currently point to, and the following row.
** AGGSTEP
** if( (regEnd--)<=0 ){
** RETURN_ROW
** if( (regStart--)<=0 ){
** AGGINVERSE
** }
** }
** }
** }
** flush:
** AGGSTEP
** while( 1 ){
** RETURN ROW
** if( csrCurrent is EOF ) break;
** if( (regStart--)<=0 ){
** AggInverse(csrStart)
** Next(csrStart)
** }
** }
**
** The pseudo-code above uses the following shorthand:
**
** AGGSTEP: invoke the aggregate xStep() function for each window function
** with arguments read from the current row of cursor csrEnd, then
** step cursor csrEnd forward one row (i.e. sqlite3BtreeNext()).
**
** RETURN_ROW: return a row to the caller based on the contents of the
** current row of csrCurrent and the current state of all
** aggregates. Then step cursor csrCurrent forward one row.
**
** AGGINVERSE: invoke the aggregate xInverse() function for each window
** functions with arguments read from the current row of cursor
** csrStart. Then step csrStart forward one row.
**
** There are two other ROWS window frames that are handled significantly
** differently from the above - "BETWEEN <expr> PRECEDING AND <expr> PRECEDING"
** and "BETWEEN <expr> FOLLOWING AND <expr> FOLLOWING". These are special
** cases because they change the order in which the three cursors (csrStart,
** csrCurrent and csrEnd) iterate through the ephemeral table. Cases that
** use UNBOUNDED or CURRENT ROW are much simpler variations on one of these
** three.
**
** ROWS BETWEEN <expr1> PRECEDING AND <expr2> PRECEDING
**
** ... loop started by sqlite3WhereBegin() ...
** if( new partition ){
** Gosub flush
** }
** Insert new row into eph table.
** if( first row of partition ){
** Rewind(csrEnd) ; Rewind(csrStart) ; Rewind(csrCurrent)
** regEnd = <expr2>
** regStart = <expr1>
** }else{
** if( (regEnd--)<=0 ){
** AGGSTEP
** }
** RETURN_ROW
** if( (regStart--)<=0 ){
** AGGINVERSE
** }
** }
** }
** flush:
** if( (regEnd--)<=0 ){
** AGGSTEP
** }
** RETURN_ROW
**
**
** ROWS BETWEEN <expr1> FOLLOWING AND <expr2> FOLLOWING
**
** ... loop started by sqlite3WhereBegin() ...
** if( new partition ){
** Gosub flush
** }
** Insert new row into eph table.
** if( first row of partition ){
** Rewind(csrEnd) ; Rewind(csrStart) ; Rewind(csrCurrent)
** regEnd = <expr2>
** regStart = regEnd - <expr1>
** }else{
** AGGSTEP
** if( (regEnd--)<=0 ){
** RETURN_ROW
** }
** if( (regStart--)<=0 ){
** AGGINVERSE
** }
** }
** }
** flush:
** AGGSTEP
** while( 1 ){
** if( (regEnd--)<=0 ){
** RETURN_ROW
** if( eof ) break;
** }
** if( (regStart--)<=0 ){
** AGGINVERSE
** if( eof ) break
** }
** }
** while( !eof csrCurrent ){
** RETURN_ROW
** }
**
** For the most part, the patterns above are adapted to support UNBOUNDED by
** assuming that it is equivalent to "infinity PRECEDING/FOLLOWING" and
** CURRENT ROW by assuming that it is equivilent to "0 PRECEDING/FOLLOWING".
** This is optimized of course - branches that will never be taken and
** conditions that are always true are omitted from the VM code. The only
** exceptional case is:
**
** ROWS BETWEEN <expr1> FOLLOWING AND UNBOUNDED FOLLOWING
**
** ... loop started by sqlite3WhereBegin() ...
** if( new partition ){
** Gosub flush
** }
** Insert new row into eph table.
** if( first row of partition ){
** Rewind(csrEnd) ; Rewind(csrStart) ; Rewind(csrCurrent)
** regStart = <expr1>
** }else{
** AGGSTEP
** }
** }
** flush:
** AGGSTEP
** while( 1 ){
** if( (regStart--)<=0 ){
** AGGINVERSE
** if( eof ) break
** }
** RETURN_ROW
** }
** while( !eof csrCurrent ){
** RETURN_ROW
** }
**
** Also requiring special handling are the cases:
**
** ROWS BETWEEN <expr1> PRECEDING AND <expr2> PRECEDING
** ROWS BETWEEN <expr1> FOLLOWING AND <expr2> FOLLOWING
**
** when (expr1 < expr2). This is detected at runtime, not by this function.
** To handle this case, the pseudo-code programs depicted above are modified
** slightly to be:
**
** ... loop started by sqlite3WhereBegin() ...
** if( new partition ){
** Gosub flush
** }
** Insert new row into eph table.
** if( first row of partition ){
** Rewind(csrEnd) ; Rewind(csrStart) ; Rewind(csrCurrent)
** regEnd = <expr2>
** regStart = <expr1>
** if( regEnd < regStart ){
** RETURN_ROW
** delete eph table contents
** continue
** }
** ...
**
** The new "continue" statement in the above jumps to the next iteration
** of the outer loop - the one started by sqlite3WhereBegin().
**
** The various GROUPS cases are implemented using the same patterns as
** ROWS. The VM code is modified slightly so that:
**
** 1. The else branch in the main loop is only taken if the row just
** added to the ephemeral table is the start of a new group. In
** other words, it becomes:
**
** ... loop started by sqlite3WhereBegin() ...
** if( new partition ){
** Gosub flush
** }
** Insert new row into eph table.
** if( first row of partition ){
** Rewind(csrEnd) ; Rewind(csrStart) ; Rewind(csrCurrent)
** regEnd = <expr2>
** regStart = <expr1>
** }else if( new group ){
** ...
** }
** }
**
** 2. Instead of processing a single row, each RETURN_ROW, AGGSTEP or
** AGGINVERSE step processes the current row of the relevant cursor and
** all subsequent rows belonging to the same group.
**
** RANGE window frames are a little different again. As for GROUPS, the
** main loop runs once per group only. And RETURN_ROW, AGGSTEP and AGGINVERSE
** deal in groups instead of rows. As for ROWS and GROUPS, there are three
** basic cases:
**
** RANGE BETWEEN <expr1> PRECEDING AND <expr2> FOLLOWING
**
** ... loop started by sqlite3WhereBegin() ...
** if( new partition ){
** Gosub flush
** }
** Insert new row into eph table.
** if( first row of partition ){
** Rewind(csrEnd) ; Rewind(csrStart) ; Rewind(csrCurrent)
** regEnd = <expr2>
** regStart = <expr1>
** }else{
** AGGSTEP
** while( (csrCurrent.key + regEnd) < csrEnd.key ){
** RETURN_ROW
** while( csrStart.key + regStart) < csrCurrent.key ){
** AGGINVERSE
** }
** }
** }
** }
** flush:
** AGGSTEP
** while( 1 ){
** RETURN ROW
** if( csrCurrent is EOF ) break;
** while( csrStart.key + regStart) < csrCurrent.key ){
** AGGINVERSE
** }
** }
** }
**
** In the above notation, "csr.key" means the current value of the ORDER BY
** expression (there is only ever 1 for a RANGE that uses an <expr> FOLLOWING
** or <expr PRECEDING) read from cursor csr.
**
** RANGE BETWEEN <expr1> PRECEDING AND <expr2> PRECEDING
**
** ... loop started by sqlite3WhereBegin() ...
** if( new partition ){
** Gosub flush
** }
** Insert new row into eph table.
** if( first row of partition ){
** Rewind(csrEnd) ; Rewind(csrStart) ; Rewind(csrCurrent)
** regEnd = <expr2>
** regStart = <expr1>
** }else{
** while( (csrEnd.key + regEnd) <= csrCurrent.key ){
** AGGSTEP
** }
** while( (csrStart.key + regStart) < csrCurrent.key ){
** AGGINVERSE
** }
** RETURN_ROW
** }
** }
** flush:
** while( (csrEnd.key + regEnd) <= csrCurrent.key ){
** AGGSTEP
** }
** while( (csrStart.key + regStart) < csrCurrent.key ){
** AGGINVERSE
** }
** RETURN_ROW
**
** RANGE BETWEEN <expr1> FOLLOWING AND <expr2> FOLLOWING
**
** ... loop started by sqlite3WhereBegin() ...
** if( new partition ){
** Gosub flush
** }
** Insert new row into eph table.
** if( first row of partition ){
** Rewind(csrEnd) ; Rewind(csrStart) ; Rewind(csrCurrent)
** regEnd = <expr2>
** regStart = <expr1>
** }else{
** AGGSTEP
** while( (csrCurrent.key + regEnd) < csrEnd.key ){
** while( (csrCurrent.key + regStart) > csrStart.key ){
** AGGINVERSE
** }
** RETURN_ROW
** }
** }
** }
** flush:
** AGGSTEP
** while( 1 ){
** while( (csrCurrent.key + regStart) > csrStart.key ){
** AGGINVERSE
** if( eof ) break "while( 1 )" loop.
** }
** RETURN_ROW
** }
** while( !eof csrCurrent ){
** RETURN_ROW
** }
**
** The text above leaves out many details. Refer to the code and comments
** below for a more complete picture.
*/
void sqlite3WindowCodeStep(
Parse *pParse, /* Parse context */
Select *p, /* Rewritten SELECT statement */
WhereInfo *pWInfo, /* Context returned by sqlite3WhereBegin() */
int regGosub, /* Register for OP_Gosub */
int addrGosub /* OP_Gosub here to return each row */
){
Window *pMWin = p->pWin;
ExprList *pOrderBy = pMWin->pOrderBy;
Vdbe *v = sqlite3GetVdbe(pParse);
int csrWrite; /* Cursor used to write to eph. table */
int csrInput = p->pSrc->a[0].iCursor; /* Cursor of sub-select */
int nInput = p->pSrc->a[0].pTab->nCol; /* Number of cols returned by sub */
int iInput; /* To iterate through sub cols */
int addrNe; /* Address of OP_Ne */
int addrGosubFlush = 0; /* Address of OP_Gosub to flush: */
int addrInteger = 0; /* Address of OP_Integer */
int addrEmpty; /* Address of OP_Rewind in flush: */
int regNew; /* Array of registers holding new input row */
int regRecord; /* regNew array in record form */
int regRowid; /* Rowid for regRecord in eph table */
int regNewPeer = 0; /* Peer values for new row (part of regNew) */
int regPeer = 0; /* Peer values for current row */
int regFlushPart = 0; /* Register for "Gosub flush_partition" */
WindowCodeArg s; /* Context object for sub-routines */
int lblWhereEnd; /* Label just before sqlite3WhereEnd() code */
int regStart = 0; /* Value of <expr> PRECEDING */
int regEnd = 0; /* Value of <expr> FOLLOWING */
assert( pMWin->eStart==TK_PRECEDING || pMWin->eStart==TK_CURRENT
|| pMWin->eStart==TK_FOLLOWING || pMWin->eStart==TK_UNBOUNDED
);
assert( pMWin->eEnd==TK_FOLLOWING || pMWin->eEnd==TK_CURRENT
|| pMWin->eEnd==TK_UNBOUNDED || pMWin->eEnd==TK_PRECEDING
);
assert( pMWin->eExclude==0 || pMWin->eExclude==TK_CURRENT
|| pMWin->eExclude==TK_GROUP || pMWin->eExclude==TK_TIES
|| pMWin->eExclude==TK_NO
);
lblWhereEnd = sqlite3VdbeMakeLabel(pParse);
/* Fill in the context object */
memset(&s, 0, sizeof(WindowCodeArg));
s.pParse = pParse;
s.pMWin = pMWin;
s.pVdbe = v;
s.regGosub = regGosub;
s.addrGosub = addrGosub;
s.current.csr = pMWin->iEphCsr;
csrWrite = s.current.csr+1;
s.start.csr = s.current.csr+2;
s.end.csr = s.current.csr+3;
/* Figure out when rows may be deleted from the ephemeral table. There
** are four options - they may never be deleted (eDelete==0), they may
** be deleted as soon as they are no longer part of the window frame
** (eDelete==WINDOW_AGGINVERSE), they may be deleted as after the row
** has been returned to the caller (WINDOW_RETURN_ROW), or they may
** be deleted after they enter the frame (WINDOW_AGGSTEP). */
switch( pMWin->eStart ){
case TK_FOLLOWING:
if( pMWin->eFrmType!=TK_RANGE
&& windowExprGtZero(pParse, pMWin->pStart)
){
s.eDelete = WINDOW_RETURN_ROW;
}
break;
case TK_UNBOUNDED:
if( windowCacheFrame(pMWin)==0 ){
if( pMWin->eEnd==TK_PRECEDING ){
if( pMWin->eFrmType!=TK_RANGE
&& windowExprGtZero(pParse, pMWin->pEnd)
){
s.eDelete = WINDOW_AGGSTEP;
}
}else{
s.eDelete = WINDOW_RETURN_ROW;
}
}
break;
default:
s.eDelete = WINDOW_AGGINVERSE;
break;
}
/* Allocate registers for the array of values from the sub-query, the
** samve values in record form, and the rowid used to insert said record
** into the ephemeral table. */