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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2006-01-10 17:35:52 +0000 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2006-01-10 17:35:52 +0000 |
| commit | ce8fd39e15894da00e1e209c47eb0936265227c5 (patch) | |
| tree | 42c3a6caebbf29733bcb36b59c3e5a7c43007ffb /src/tutorial/funcs.c | |
| parent | ad24b8e6eef1f860c888ecfd2440c4761e3a9910 (diff) | |
| download | postgresql-ce8fd39e15894da00e1e209c47eb0936265227c5.tar.gz postgresql-ce8fd39e15894da00e1e209c47eb0936265227c5.zip | |
Improve patternsel() by applying the operator itself to each value
listed in the column's most-common-values statistics entry. This gives
us an exact selectivity result for the portion of the column population
represented by the MCV list, which can be a big leg up in accuracy if
that's a large fraction of the population. The heuristics involving
pattern contents and prefix are applied only to the part of the population
not included in the MCV list.
Diffstat (limited to 'src/tutorial/funcs.c')
0 files changed, 0 insertions, 0 deletions