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| author | Robert Haas <rhaas@postgresql.org> | 2012-01-27 12:40:37 -0500 |
|---|---|---|
| committer | Robert Haas <rhaas@postgresql.org> | 2012-01-27 12:40:37 -0500 |
| commit | eb6af016fc04392c41106ac866072914bf66ecd0 (patch) | |
| tree | b5549d197c9501f1fbdbea3a63ef74dc5787a155 /doc/src | |
| parent | db6de5b71ef2d91dde94fc0de8adf45372bc332d (diff) | |
| download | postgresql-eb6af016fc04392c41106ac866072914bf66ecd0.tar.gz postgresql-eb6af016fc04392c41106ac866072914bf66ecd0.zip | |
Document that COUNT(*) might not need a seq scan any more.
Noted by Josh Kupershmidt.
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/func.sgml | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml index 219ba9abf39..ec140040843 100644 --- a/doc/src/sgml/func.sgml +++ b/doc/src/sgml/func.sgml @@ -11102,8 +11102,10 @@ SELECT b1 = ANY((SELECT b2 FROM t2 ...)) FROM t1 ...; <programlisting> SELECT count(*) FROM sometable; </programlisting> - will be executed by <productname>PostgreSQL</productname> using a - sequential scan of the entire table. + will require effort proportional to the size of the table: + <productname>PostgreSQL</productname> will need to scan either the + entire table or the entirety of an index which includes all rows in + the table. </para> </note> |