| // Copyright 2015 The LUCI Authors. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| // Package bigtable provides an implementation of the Storage interface backed |
| // by Google Cloud Platform's BigTable. |
| // |
| // # Intermediate Log Table |
| // |
| // The Intermediate Log Table stores LogEntry protobufs that have been ingested, |
| // but haven't yet been archived. It is a tall table whose rows are keyed off |
| // of the log's (Path,Stream-Index) in that order. |
| // |
| // Each entry in the table will contain the following schema: |
| // - Column Family "log" |
| // - Column "data": the LogEntry raw protobuf data. Soft size limit of ~1MB. |
| // |
| // The log path is the composite of the log's (Prefix, Name) properties. Logs |
| // belonging to the same stream will share the same path, so they will be |
| // clustered together and suitable for efficient iteration. Immediately |
| // following the path will be the log's stream index. |
| // |
| // [ 20 bytes ] ~ [ 1-5 bytes ] |
| // B64(SHA256(Path(Prefix, Name))) + '~' + HEX(cmpbin(StreamIndex)) |
| // |
| // As there is no (technical) size constraint to either the Prefix or Name |
| // values, they will both be hashed using SHA256 to produce a unique key |
| // representing that specific log stream. |
| // |
| // This allows a key to be generated representing "immediately after the row" |
| // by appending two '~' characters to the base hash. Since the second '~' |
| // character is always greater than any HEX(cmpbin(*)) value, this will |
| // effectively upper-bound the row. |
| // |
| // "cmpbin" (go.chromium.org/luci/common/cmpbin) will be used to format the |
| // stream index. It is a variable-width number encoding scheme that offers the |
| // guarantee that byte-sorted encoded numbers will maintain the same order as |
| // the numbers themselves. |
| package bigtable |
