1 files changed, 169 insertions, 0 deletions
diff --git a/src/backend/backup/walsummaryfuncs.c b/src/backend/backup/walsummaryfuncs.c
new file mode 100644
index 00000000000..a1f69ad4bac
--- /dev/null
+++ b/src/backend/backup/walsummaryfuncs.c
@@ -0,0 +1,169 @@
+/*-------------------------------------------------------------------------
+ *
+ * walsummaryfuncs.c
+ *	  SQL-callable functions for accessing WAL summary data.
+ *
+ * Portions Copyright (c) 2010-2022, PostgreSQL Global Development Group
+ *
+ * src/backend/backup/walsummaryfuncs.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "backup/walsummary.h"
+#include "common/blkreftable.h"
+#include "funcapi.h"
+#include "miscadmin.h"
+#include "utils/fmgrprotos.h"
+#include "utils/pg_lsn.h"
+
+#define NUM_WS_ATTS			3
+#define NUM_SUMMARY_ATTS	6
+#define MAX_BLOCKS_PER_CALL	256
+
+/*
+ * List the WAL summary files available in pg_wal/summaries.
+ */
+Datum
+pg_available_wal_summaries(PG_FUNCTION_ARGS)
+{
+	ReturnSetInfo *rsi;
+	List	   *wslist;
+	ListCell   *lc;
+	Datum		values[NUM_WS_ATTS];
+	bool		nulls[NUM_WS_ATTS];
+
+	InitMaterializedSRF(fcinfo, 0);
+	rsi = (ReturnSetInfo *) fcinfo->resultinfo;
+
+	memset(nulls, 0, sizeof(nulls));
+
+	wslist = GetWalSummaries(0, InvalidXLogRecPtr, InvalidXLogRecPtr);
+	foreach(lc, wslist)
+	{
+		WalSummaryFile *ws = (WalSummaryFile *) lfirst(lc);
+		HeapTuple	tuple;
+
+		CHECK_FOR_INTERRUPTS();
+
+		values[0] = Int64GetDatum((int64) ws->tli);
+		values[1] = LSNGetDatum(ws->start_lsn);
+		values[2] = LSNGetDatum(ws->end_lsn);
+
+		tuple = heap_form_tuple(rsi->setDesc, values, nulls);
+		tuplestore_puttuple(rsi->setResult, tuple);
+	}
+
+	return (Datum) 0;
+}
+
+/*
+ * List the contents of a WAL summary file identified by TLI, start LSN,
+ * and end LSN.
+ */
+Datum
+pg_wal_summary_contents(PG_FUNCTION_ARGS)
+{
+	ReturnSetInfo *rsi;
+	Datum		values[NUM_SUMMARY_ATTS];
+	bool		nulls[NUM_SUMMARY_ATTS];
+	WalSummaryFile ws;
+	WalSummaryIO io;
+	BlockRefTableReader *reader;
+	int64		raw_tli;
+	RelFileLocator rlocator;
+	ForkNumber	forknum;
+	BlockNumber limit_block;
+
+	InitMaterializedSRF(fcinfo, 0);
+	rsi = (ReturnSetInfo *) fcinfo->resultinfo;
+	memset(nulls, 0, sizeof(nulls));
+
+	/*
+	 * Since the timeline could at least in theory be more than 2^31, and
+	 * since we don't have unsigned types at the SQL level, it is passed as a
+	 * 64-bit integer. Test whether it's out of range.
+	 */
+	raw_tli = PG_GETARG_INT64(0);
+	if (raw_tli < 1 || raw_tli > PG_INT32_MAX)
+		ereport(ERROR,
+				errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				errmsg("invalid timeline %lld", (long long) raw_tli));
+
+	/* Prepare to read the specified WAL summry file. */
+	ws.tli = (TimeLineID) raw_tli;
+	ws.start_lsn = PG_GETARG_LSN(1);
+	ws.end_lsn = PG_GETARG_LSN(2);
+	io.filepos = 0;
+	io.file = OpenWalSummaryFile(&ws, false);
+	reader = CreateBlockRefTableReader(ReadWalSummary, &io,
+									   FilePathName(io.file),
+									   ReportWalSummaryError, NULL);
+
+	/* Loop over relation forks. */
+	while (BlockRefTableReaderNextRelation(reader, &rlocator, &forknum,
+										   &limit_block))
+	{
+		BlockNumber blocks[MAX_BLOCKS_PER_CALL];
+		HeapTuple	tuple;
+
+		CHECK_FOR_INTERRUPTS();
+
+		values[0] = ObjectIdGetDatum(rlocator.relNumber);
+		values[1] = ObjectIdGetDatum(rlocator.spcOid);
+		values[2] = ObjectIdGetDatum(rlocator.dbOid);
+		values[3] = Int16GetDatum((int16) forknum);
+
+		/* Loop over blocks within the current relation fork. */
+		while (1)
+		{
+			unsigned	nblocks;
+			unsigned	i;
+
+			CHECK_FOR_INTERRUPTS();
+
+			nblocks = BlockRefTableReaderGetBlocks(reader, blocks,
+												   MAX_BLOCKS_PER_CALL);
+			if (nblocks == 0)
+				break;
+
+			/*
+			 * For each block that we specifically know to have been modified,
+			 * emit a row with that block number and limit_block = false.
+			 */
+			values[5] = BoolGetDatum(false);
+			for (i = 0; i < nblocks; ++i)
+			{
+				values[4] = Int64GetDatum((int64) blocks[i]);
+
+				tuple = heap_form_tuple(rsi->setDesc, values, nulls);
+				tuplestore_puttuple(rsi->setResult, tuple);
+			}
+
+			/*
+			 * If the limit block is not InvalidBlockNumber, emit an exta row
+			 * with that block number and limit_block = true.
+			 *
+			 * There is no point in doing this when the limit_block is
+			 * InvalidBlockNumber, because no block with that number or any
+			 * higher number can ever exist.
+			 */
+			if (BlockNumberIsValid(limit_block))
+			{
+				values[4] = Int64GetDatum((int64) limit_block);
+				values[5] = BoolGetDatum(true);
+
+				tuple = heap_form_tuple(rsi->setDesc, values, nulls);
+				tuplestore_puttuple(rsi->setResult, tuple);
+			}
+		}
+	}
+
+	/* Cleanup */
+	DestroyBlockRefTableReader(reader);
+	FileClose(io.file);
+
+	return (Datum) 0;
+}