From: Tomas Vondra Date: Thu, 27 Jun 2019 16:14:25 +0000 (+0200) Subject: Update reference to sampling algorithm in analyze.c X-Git-Tag: REL_11_5~64 X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=803cdf22a2d395653496702af789ccae7c17e18c;p=postgresql Update reference to sampling algorithm in analyze.c Commit 83e176ec1 moved row sampling functions from analyze.c to utils/misc/sampling.c, but failed to update comment referring to the sampling algorithm from Jeff Vitter's paper. Correct the comment by pointing to utils/misc/sampling.c. Author: Etsuro Fujita Discussion: https://postgr.es/m/CAPmGK154gp%2BQd%3DcorQOv%2BPmbyVyZBjp_%2Bhb766UJeD1e_ie6XQ%40mail.gmail.com --- diff --git a/src/backend/commands/analyze.c b/src/backend/commands/analyze.c index d5d8cefc2f..98be84e1ad 100644 --- a/src/backend/commands/analyze.c +++ b/src/backend/commands/analyze.c @@ -1207,13 +1207,13 @@ acquire_sample_rows(Relation onerel, int elevel, * The first targrows sample rows are simply copied into the * reservoir. Then we start replacing tuples in the sample * until we reach the end of the relation. This algorithm is - * from Jeff Vitter's paper (see full citation below). It - * works by repeatedly computing the number of tuples to skip - * before selecting a tuple, which replaces a randomly chosen - * element of the reservoir (current set of tuples). At all - * times the reservoir is a true random sample of the tuples - * we've passed over so far, so when we fall off the end of - * the relation we're done. + * from Jeff Vitter's paper (see full citation in + * utils/misc/sampling.c). It works by repeatedly computing + * the number of tuples to skip before selecting a tuple, + * which replaces a randomly chosen element of the reservoir + * (current set of tuples). At all times the reservoir is a + * true random sample of the tuples we've passed over so far, + * so when we fall off the end of the relation we're done. */ if (numrows < targrows) rows[numrows++] = heap_copytuple(&targtuple);