v12-0001-Remove-obsolete-BlockSampler_HasMore.patch

From c3b8df8e4720d8b0dfb4c892c0aa3ddaef8f401f Mon Sep 17 00:00:00 2001
From: Thomas Munro <tmunro@postgresql.org>
Date: Mon, 8 Apr 2024 14:38:58 +1200
Subject: [PATCH v12] Remove obsolete BlockSampler_HasMore().

Commit 041b9680 stopped using BlockSampler_HasMore() for flow control in
acquire_sample_rows(). There seems to be little use for it now. We can
just return InvalidBlockNumber from BlockSampler_Next() when
BlockSample_HasMore() would have returned false.

Author: Melanie Plageman <melanieplageman@gmail.com>
Author: Nazir Bilal Yavuz <byavuz81@gmail.com>
Reviewed-by: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/flat/CAN55FZ0UhXqk9v3y-zW_fp4-WCp43V8y0A72xPmLkOM%2B6M%2BmJg%40mail.gmail.com
---
 src/backend/commands/analyze.c    |  4 +---
 src/backend/utils/misc/sampling.c | 10 +++-------
 src/include/utils/sampling.h      |  1 -
 3 files changed, 4 insertions(+), 11 deletions(-)

diff --git a/src/backend/commands/analyze.c b/src/backend/commands/analyze.c
index da27a13a3f..e9fa3470cf 100644
--- a/src/backend/commands/analyze.c
+++ b/src/backend/commands/analyze.c
@@ -1111,9 +1111,7 @@ block_sampling_read_stream_next(ReadStream *stream,
 								void *callback_private_data,
 								void *per_buffer_data)
 {
-	BlockSamplerData *bs = callback_private_data;
-
-	return BlockSampler_HasMore(bs) ? BlockSampler_Next(bs) : InvalidBlockNumber;
+	return BlockSampler_Next(callback_private_data);
 }
 
 /*
diff --git a/src/backend/utils/misc/sampling.c b/src/backend/utils/misc/sampling.c
index 933db06702..6e2bca9739 100644
--- a/src/backend/utils/misc/sampling.c
+++ b/src/backend/utils/misc/sampling.c
@@ -54,12 +54,6 @@ BlockSampler_Init(BlockSampler bs, BlockNumber nblocks, int samplesize,
 	return Min(bs->n, bs->N);
 }
 
-bool
-BlockSampler_HasMore(BlockSampler bs)
-{
-	return (bs->t < bs->N) && (bs->m < bs->n);
-}
-
 BlockNumber
 BlockSampler_Next(BlockSampler bs)
 {
@@ -68,7 +62,9 @@ BlockSampler_Next(BlockSampler bs)
 	double		p;				/* probability to skip block */
 	double		V;				/* random */
 
-	Assert(BlockSampler_HasMore(bs));	/* hence K > 0 and k > 0 */
+	/* Return if no remaining blocks or no blocks to sample */
+	if (K <= 0 || k <= 0)
+		return InvalidBlockNumber;
 
 	if ((BlockNumber) k >= K)
 	{
diff --git a/src/include/utils/sampling.h b/src/include/utils/sampling.h
index be48ee52ba..fb5d6820a2 100644
--- a/src/include/utils/sampling.h
+++ b/src/include/utils/sampling.h
@@ -38,7 +38,6 @@ typedef BlockSamplerData *BlockSampler;
 
 extern BlockNumber BlockSampler_Init(BlockSampler bs, BlockNumber nblocks,
 									 int samplesize, uint32 randseed);
-extern bool BlockSampler_HasMore(BlockSampler bs);
 extern BlockNumber BlockSampler_Next(BlockSampler bs);
 
 /* Reservoir sampling methods */
-- 
2.44.0