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| author | Bruce Momjian <bruce@momjian.us> | 1999-02-19 05:18:06 +0000 |
|---|---|---|
| committer | Bruce Momjian <bruce@momjian.us> | 1999-02-19 05:18:06 +0000 |
| commit | 612b8434e40edc299e38bd6e4d7ac07183513118 (patch) | |
| tree | 1e6627371e408c408e80126035e2014584cd8a38 /src/backend/optimizer/README | |
| parent | 8ab72a38df82a863f787c65a4b8998893a946377 (diff) | |
| download | postgresql-612b8434e40edc299e38bd6e4d7ac07183513118.tar.gz | |
optimizer cleanup
Diffstat (limited to 'src/backend/optimizer/README')
| -rw-r--r-- | src/backend/optimizer/README | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/src/backend/optimizer/README b/src/backend/optimizer/README index 2b6ff52c5f..b25d7fb5f1 100644 --- a/src/backend/optimizer/README +++ b/src/backend/optimizer/README @@ -7,7 +7,9 @@ The optimizer generates optimial query plans by doing several steps: it. Find each way of accessing the relation, called a Path, including sequential and index scans, and add it to RelOptInfo.pathlist. Also create RelOptInfo.joininfo that lists all the joins that involve this -relation. +relation. For example, the WHERE clause "tab1.col1 = tab2.col1" +generates a JoinInfo for tab1 listing tab2 as an unjoined relation, and +tab2's joininfo shows tab1 as an unjoined relation. 2) Join each RelOptInfo to other RelOptInfo as specified in RelOptInfo.joininfo. At this point each RelOptInfo is a single |