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authorTom Lane <tgl@sss.pgh.pa.us>2005-01-28 20:35:14 +0000
committerTom Lane <tgl@sss.pgh.pa.us>2005-01-28 20:35:14 +0000
commit7c67dcacd83c885618a58936df627a17470d9991 (patch)
tree759f3d24900f14b55cd260b5ef8bddc8fa22df2b /src/backend/utils/adt/array_userfuncs.c
parenta098f533d15efe5552c0b6cd661cc123231c8c54 (diff)
downloadpostgresql-7c67dcacd83c885618a58936df627a17470d9991.tar.gz
postgresql-7c67dcacd83c885618a58936df627a17470d9991.zip
When dealing with multiple grouping columns coming from the same table,
clamp the estimated number of groups to table row count over 10, instead of table row count; this reflects a heuristic that people probably won't group over a near-unique set of columns, and the knowledge that we don't currently have any way to estimate the correlation of the columns better than guessing. This change creates a trivial plan change in one of the regression tests.
Diffstat (limited to 'src/backend/utils/adt/array_userfuncs.c')
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