v3-0001-Few-optimizations-around-block-references-in-pg_w.patch

From 153d1d8ae7f03471aa74b685d20eb110ba7eda98 Mon Sep 17 00:00:00 2001
From: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Date: Sat, 18 Mar 2023 04:01:46 +0000
Subject: [PATCH v3] Few optimizations around block references in pg_walinspect

---
 contrib/pg_walinspect/pg_walinspect.c | 29 +++++++++++++++++++--------
 1 file changed, 21 insertions(+), 8 deletions(-)

diff --git a/contrib/pg_walinspect/pg_walinspect.c b/contrib/pg_walinspect/pg_walinspect.c
index 3b3215daf5..c3ed31db8f 100644
--- a/contrib/pg_walinspect/pg_walinspect.c
+++ b/contrib/pg_walinspect/pg_walinspect.c
@@ -199,9 +199,12 @@ GetWALRecordInfo(XLogReaderState *record, Datum *values,
 	initStringInfo(&rec_desc);
 	desc.rm_desc(&rec_desc, record);
 
-	/* Block references. */
-	initStringInfo(&rec_blk_ref);
-	XLogRecGetBlockRefInfo(record, false, true, &rec_blk_ref, &fpi_len);
+	/* Get block references, if any. */
+	if (XLogRecHasAnyBlockRefs(record))
+	{
+		initStringInfo(&rec_blk_ref);
+		XLogRecGetBlockRefInfo(record, false, true, &rec_blk_ref, &fpi_len);
+	}
 
 	main_data_len = XLogRecGetDataLen(record);
 
@@ -215,7 +218,12 @@ GetWALRecordInfo(XLogReaderState *record, Datum *values,
 	values[i++] = UInt32GetDatum(main_data_len);
 	values[i++] = UInt32GetDatum(fpi_len);
 	values[i++] = CStringGetTextDatum(rec_desc.data);
-	values[i++] = CStringGetTextDatum(rec_blk_ref.data);
+
+	/* Output block references, if any. */
+	if (XLogRecHasAnyBlockRefs(record))
+		values[i++] = CStringGetTextDatum(rec_blk_ref.data);
+	else
+		nulls[i++] = true;
 
 	Assert(i == ncols);
 }
@@ -377,6 +385,12 @@ pg_get_wal_block_info(PG_FUNCTION_ARGS)
 	while (ReadNextXLogRecord(xlogreader) &&
 		   xlogreader->EndRecPtr <= end_lsn)
 	{
+		CHECK_FOR_INTERRUPTS();
+
+		/* Get block references, if any, otherwise continue. */
+		if (!XLogRecHasAnyBlockRefs(xlogreader))
+			continue;
+
 		/* Use the tmp context so we can clean up after each tuple is done */
 		old_cxt = MemoryContextSwitchTo(tmp_cxt);
 
@@ -385,8 +399,6 @@ pg_get_wal_block_info(PG_FUNCTION_ARGS)
 		/* clean up and switch back */
 		MemoryContextSwitchTo(old_cxt);
 		MemoryContextReset(tmp_cxt);
-
-		CHECK_FOR_INTERRUPTS();
 	}
 
 	MemoryContextDelete(tmp_cxt);
@@ -483,8 +495,6 @@ GetWALRecordsInfo(FunctionCallInfo fcinfo, XLogRecPtr start_lsn,
 #define PG_GET_WAL_RECORDS_INFO_COLS 11
 	XLogReaderState *xlogreader;
 	ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
-	Datum		values[PG_GET_WAL_RECORDS_INFO_COLS] = {0};
-	bool		nulls[PG_GET_WAL_RECORDS_INFO_COLS] = {0};
 	MemoryContext old_cxt;
 	MemoryContext tmp_cxt;
 
@@ -501,6 +511,9 @@ GetWALRecordsInfo(FunctionCallInfo fcinfo, XLogRecPtr start_lsn,
 	while (ReadNextXLogRecord(xlogreader) &&
 		   xlogreader->EndRecPtr <= end_lsn)
 	{
+		Datum		values[PG_GET_WAL_RECORDS_INFO_COLS] = {0};
+		bool		nulls[PG_GET_WAL_RECORDS_INFO_COLS] = {0};
+
 		/* Use the tmp context so we can clean up after each tuple is done */
 		old_cxt = MemoryContextSwitchTo(tmp_cxt);
 
-- 
2.34.1