diff options
| author | Bruce Momjian | 2021-12-22 21:29:16 +0000 |
|---|---|---|
| committer | Bruce Momjian | 2021-12-22 21:29:16 +0000 |
| commit | f163cc8f4d6952da79eda461b67626d1fdfafed0 (patch) | |
| tree | 756394174e4f407c84aa47e1af455a0ee5642481 /doc/src | |
| parent | 1a0ef5e2cc63797feec1bbbf2ca89906fed76bfb (diff) | |
doc: clarify when expression indexes evaluate their expressions
Only non-HOT updates evaluate the index expression.
Reported-by: Chris Lowder
Discussion: https://postgr.es/m/163967385701.26064.15365003480975321072@wrigleys.postgresql.org
Backpatch-through: 10
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/indices.sgml | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/doc/src/sgml/indices.sgml b/doc/src/sgml/indices.sgml index 210a9e0adfc..ec2d16d94ef 100644 --- a/doc/src/sgml/indices.sgml +++ b/doc/src/sgml/indices.sgml @@ -725,8 +725,8 @@ CREATE INDEX people_names ON people ((first_name || ' ' || last_name)); <para> Index expressions are relatively expensive to maintain, because the - derived expression(s) must be computed for each row upon insertion - and whenever it is updated. However, the index expressions are + derived expression(s) must be computed for each row insertion + and non-HOT update. However, the index expressions are <emphasis>not</emphasis> recomputed during an indexed search, since they are already stored in the index. In both examples above, the system sees the query as just <literal>WHERE indexedcolumn = 'constant'</literal> |