v2699-0003-Force-all-callers-to-encode-no-matter-how-smal.patch.txt

From 82c1f639aaa64cc943af3b53294a63d5d8f7a9b9 Mon Sep 17 00:00:00 2001
From: John Naylor <john.naylor@postgresql.org>
Date: Sat, 11 Feb 2023 11:51:32 +0700
Subject: [PATCH v2699 3/3] Force all callers to encode, no matter how small
 the expected offset

---
 src/backend/access/common/tidstore.c | 36 +++++-----------------------
 1 file changed, 6 insertions(+), 30 deletions(-)

diff --git a/src/backend/access/common/tidstore.c b/src/backend/access/common/tidstore.c
index 3d384cf645..ff8e66936e 100644
--- a/src/backend/access/common/tidstore.c
+++ b/src/backend/access/common/tidstore.c
@@ -99,7 +99,6 @@ typedef struct TidStoreControl
 	size_t	max_bytes;		/* the maximum bytes a TidStore can use */
 	int		max_offset;		/* the maximum offset number */
 	int		offset_nbits;	/* the number of bits required for max_offset */
-	bool	encode_tids;	/* do we use tid encoding? */
 	int		offset_key_nbits;	/* the number of bits of a offset number
 								 * used for the key */
 
@@ -224,21 +223,15 @@ tidstore_create(size_t max_bytes, int max_offset, dsa_area *area)
 	ts->control->max_offset = max_offset;
 	ts->control->offset_nbits = pg_ceil_log2_32(max_offset);
 
+	if (ts->control->offset_nbits < TIDSTORE_VALUE_NBITS)
+		ts->control->offset_nbits = TIDSTORE_VALUE_NBITS;
+
 	/*
 	 * We use tid encoding if the number of bits for the offset number doesn't
 	 * fix in a value, uint64.
 	 */
-	if (ts->control->offset_nbits > TIDSTORE_VALUE_NBITS)
-	{
-		ts->control->encode_tids = true;
-		ts->control->offset_key_nbits =
-			ts->control->offset_nbits - TIDSTORE_VALUE_NBITS;
-	}
-	else
-	{
-		ts->control->encode_tids = false;
-		ts->control->offset_key_nbits = 0;
-	}
+	ts->control->offset_key_nbits =
+		ts->control->offset_nbits - TIDSTORE_VALUE_NBITS;
 
 	return ts;
 }
@@ -643,12 +636,6 @@ tidstore_iter_extract_tids(TidStoreIter *iter, uint64 key, uint64 val)
 		uint64	tid_i;
 		OffsetNumber	off;
 
-		if (i > iter->ts->control->max_offset)
-		{
-			Assert(!iter->ts->control->encode_tids);
-			break;
-		}
-
 		if ((val & (UINT64CONST(1) << i)) == 0)
 			continue;
 
@@ -668,10 +655,7 @@ tidstore_iter_extract_tids(TidStoreIter *iter, uint64 key, uint64 val)
 static inline BlockNumber
 key_get_blkno(TidStore *ts, uint64 key)
 {
-	if (ts->control->encode_tids)
-		return (BlockNumber) (key >> ts->control->offset_key_nbits);
-
-	return (BlockNumber) key;
+	return (BlockNumber) (key >> ts->control->offset_key_nbits);
 }
 
 /* Encode a tid to key and offset */
@@ -691,14 +675,6 @@ encode_key_off(TidStore *ts, BlockNumber block, uint32 offset, uint32 *off)
 	uint64 key;
 	uint64 tid_i;
 
-	if (!ts->control->encode_tids)
-	{
-		*off = offset;
-
-		/* Use the block number as the key */
-		return (int64) block;
-	}
-
 	tid_i = offset | ((uint64) block << ts->control->offset_nbits);
 
 	*off = tid_i & ((UINT64CONST(1) << TIDSTORE_VALUE_NBITS) - 1);
-- 
2.39.1