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| author | Daniel Gustafsson <dgustafsson@postgresql.org> | 2023-04-12 16:16:12 +0200 |
|---|---|---|
| committer | Daniel Gustafsson <dgustafsson@postgresql.org> | 2023-04-12 16:16:12 +0200 |
| commit | 91199dd281f11b8fdd214210cb608012a9aaef88 (patch) | |
| tree | 09ab782399b129b927b618d9a8bfeadc81a553b2 /doc | |
| parent | 5f38a2034e4f18ad3a57421f070ae01c32137ef1 (diff) | |
| download | postgresql-91199dd281f11b8fdd214210cb608012a9aaef88.tar.gz | |
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 <acronym>
markup but were missing from the acronyms page.
Reported-by: Eric Mutta <eric.mutta@gmail.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/166112292492.654.5377188452604176150@wrigleys.postgresql.org
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/src/sgml/acronyms.sgml | 20 | ||||
| -rw-r--r-- | doc/src/sgml/planstats.sgml | 2 |
2 files changed, 21 insertions, 1 deletions
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 @@ -409,6 +409,26 @@ </varlistentry> <varlistentry> + <term><acronym>MCF</acronym></term> + <listitem> + <para> + Most Common Frequency, that is the frequency associated with some + Most Common Value + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><acronym>MCV</acronym></term> + <listitem> + <para> + Most Common Value, one of the values appearing most often within a + particular table column + </para> + </listitem> + </varlistentry> + + <varlistentry> <term><acronym>MITM</acronym></term> <listitem> <para> 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'; <acronym>MCV</acronym>s: <programlisting> -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 |