From 91199dd281f11b8fdd214210cb608012a9aaef88 Mon Sep 17 00:00:00 2001 From: Daniel Gustafsson Date: Wed, 12 Apr 2023 16:16:12 +0200 Subject: [PATCH] doc: Reword unexplained abbreviation The previous wording used MVF to indicate the Most Common Values' Frequencies, but the abbreviation was never explained or defined. Reword to mcv_freqs to make the use clearer. Also add MCF and MCV as acronyms as they were using markup but were missing from the acronyms page. Reported-by: Eric Mutta Reviewed-by: Tom Lane Discussion: https://postgr.es/m/166112292492.654.5377188452604176150@wrigleys.postgresql.org --- doc/src/sgml/acronyms.sgml | 20 ++++++++++++++++++++ doc/src/sgml/planstats.sgml | 2 +- 2 files changed, 21 insertions(+), 1 deletion(-) diff --git a/doc/src/sgml/acronyms.sgml b/doc/src/sgml/acronyms.sgml index 2df6559acc..a60ff54a6c 100644 --- a/doc/src/sgml/acronyms.sgml +++ b/doc/src/sgml/acronyms.sgml @@ -408,6 +408,26 @@ + + MCF + + + Most Common Frequency, that is the frequency associated with some + Most Common Value + + + + + + MCV + + + Most Common Value, one of the values appearing most often within a + particular table column + + + + MITM diff --git a/doc/src/sgml/planstats.sgml b/doc/src/sgml/planstats.sgml index df85ea5eea..d2b84b301f 100644 --- a/doc/src/sgml/planstats.sgml +++ b/doc/src/sgml/planstats.sgml @@ -203,7 +203,7 @@ EXPLAIN SELECT * FROM tenk1 WHERE stringu1 = 'xxx'; MCVs: -selectivity = (1 - sum(mvf))/(num_distinct - num_mcv) +selectivity = (1 - sum(mcv_freqs))/(num_distinct - num_mcv) = (1 - (0.00333333 + 0.003 + 0.003 + 0.003 + 0.003 + 0.003 + 0.003 + 0.003 + 0.003 + 0.003))/(676 - 10) = 0.0014559