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 d5d8cefc2f5a38073bd3e7d40af318b36b822bf4..98be84e1ad769056f81473138bd41a4d79e92f75 100644 (file)
--- 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);