Expose control file data via SQL accessible functions.

Add four new SQL accessible functions: pg_control_system(),
pg_control_checkpoint(), pg_control_recovery(), and pg_control_init()
which expose a subset of the control file data.

Along the way move the code to read and validate the control file to
src/common, where it can be shared by the new backend functions
and the original pg_controldata frontend program.

Patch by me, significant input, testing, and review by Michael Paquier.

1 files changed, 341 insertions, 0 deletions

diff --git a/src/backend/utils/misc/pg_controldata.c b/src/backend/utils/misc/pg_controldata.c
new file mode 100644
index 00000000000..8552c0713b2
--- /dev/null
+++ b/src/backend/utils/misc/pg_controldata.c
@@ -0,0 +1,341 @@
+/*-------------------------------------------------------------------------
+ *
+ * pg_controldata.c
+ *
+ * Routines to expose the contents of the control data file via
+ * a set of SQL functions.
+ *
+ * Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * IDENTIFICATION
+ *	  src/backend/utils/misc/pg_controldata.c
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "funcapi.h"
+#include "miscadmin.h"
+#include "access/htup_details.h"
+#include "access/xlog_internal.h"
+#include "catalog/pg_control.h"
+#include "catalog/pg_type.h"
+#include "common/controldata_utils.h"
+#include "utils/builtins.h"
+#include "utils/pg_lsn.h"
+#include "utils/timestamp.h"
+
+Datum
+pg_control_system(PG_FUNCTION_ARGS)
+{
+	Datum				values[4];
+	bool				nulls[4];
+	TupleDesc			tupdesc;
+	HeapTuple			htup;
+	ControlFileData	   *ControlFile;
+
+	/*
+	 * Construct a tuple descriptor for the result row.  This must match this
+	 * function's pg_proc entry!
+	 */
+	tupdesc = CreateTemplateTupleDesc(4, false);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 1, "pg_control_version",
+					   INT4OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 2, "catalog_version_no",
+					   INT4OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 3, "system_identifier",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 4, "pg_control_last_modified",
+					   TIMESTAMPTZOID, -1, 0);
+	tupdesc = BlessTupleDesc(tupdesc);
+
+	/* read the control file */
+	ControlFile = get_controlfile(DataDir, NULL);
+
+	values[0] = Int32GetDatum(ControlFile->pg_control_version);
+	nulls[0] = false;
+
+	values[1] = Int32GetDatum(ControlFile->catalog_version_no);
+	nulls[1] = false;
+
+	values[2] = Int64GetDatum(ControlFile->system_identifier);
+	nulls[2] = false;
+
+	values[3] = TimestampTzGetDatum(time_t_to_timestamptz(ControlFile->time));
+	nulls[3] = false;
+
+	htup = heap_form_tuple(tupdesc, values, nulls);
+
+	PG_RETURN_DATUM(HeapTupleGetDatum(htup));
+}
+
+Datum
+pg_control_checkpoint(PG_FUNCTION_ARGS)
+{
+	Datum				values[19];
+	bool				nulls[19];
+	TupleDesc			tupdesc;
+	HeapTuple			htup;
+	ControlFileData	   *ControlFile;
+	XLogSegNo			segno;
+	char				xlogfilename[MAXFNAMELEN];
+
+	/*
+	 * Construct a tuple descriptor for the result row.  This must match this
+	 * function's pg_proc entry!
+	 */
+	tupdesc = CreateTemplateTupleDesc(19, false);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 1, "checkpoint_location",
+					   LSNOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 2, "prior_location",
+					   LSNOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 3, "redo_location",
+					   LSNOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 4, "redo_wal_file",
+					   TEXTOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 5, "timeline_id",
+					   INT4OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 6, "prev_timeline_id",
+					   INT4OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 7, "full_page_writes",
+					   BOOLOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 8, "next_xid",
+					   TEXTOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 9, "next_oid",
+					   OIDOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 10, "next_multixact_id",
+					   XIDOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 11, "next_multi_offset",
+					   XIDOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 12, "oldest_xid",
+					   XIDOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 13, "oldest_xid_dbid",
+					   OIDOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 14, "oldest_active_xid",
+					   XIDOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 15, "oldest_multi_xid",
+					   XIDOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 16, "oldest_multi_dbid",
+					   OIDOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 17, "oldest_commit_ts_xid",
+					   XIDOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 18, "newest_commit_ts_xid",
+					   XIDOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 19, "checkpoint_time",
+					   TIMESTAMPTZOID, -1, 0);
+	tupdesc = BlessTupleDesc(tupdesc);
+
+	/* Read the control file. */
+	ControlFile = get_controlfile(DataDir, NULL);
+
+	/*
+	 * Calculate name of the WAL file containing the latest checkpoint's REDO
+	 * start point.
+	 */
+	XLByteToSeg(ControlFile->checkPointCopy.redo, segno);
+	XLogFileName(xlogfilename, ControlFile->checkPointCopy.ThisTimeLineID, segno);
+
+	/* Populate the values and null arrays */
+	values[0] = LSNGetDatum(ControlFile->checkPoint);
+	nulls[0] = false;
+
+	values[1] = LSNGetDatum(ControlFile->prevCheckPoint);
+	nulls[1] = false;
+
+	values[2] = LSNGetDatum(ControlFile->checkPointCopy.redo);
+	nulls[2] = false;
+
+	values[3] = CStringGetTextDatum(xlogfilename);
+	nulls[3] = false;
+
+	values[4] = Int32GetDatum(ControlFile->checkPointCopy.ThisTimeLineID);
+	nulls[4] = false;
+
+	values[5] = Int32GetDatum(ControlFile->checkPointCopy.PrevTimeLineID);
+	nulls[5] = false;
+
+	values[6] = BoolGetDatum(ControlFile->checkPointCopy.fullPageWrites);
+	nulls[6] = false;
+
+	values[7] = CStringGetTextDatum(psprintf("%u:%u",
+								ControlFile->checkPointCopy.nextXidEpoch,
+								ControlFile->checkPointCopy.nextXid));
+	nulls[7] = false;
+
+	values[8] = ObjectIdGetDatum(ControlFile->checkPointCopy.nextOid);
+	nulls[8] = false;
+
+	values[9] = TransactionIdGetDatum(ControlFile->checkPointCopy.nextMulti);
+	nulls[9] = false;
+
+	values[10] = TransactionIdGetDatum(ControlFile->checkPointCopy.nextMultiOffset);
+	nulls[10] = false;
+
+	values[11] = TransactionIdGetDatum(ControlFile->checkPointCopy.oldestXid);
+	nulls[11] = false;
+
+	values[12] = ObjectIdGetDatum(ControlFile->checkPointCopy.oldestXidDB);
+	nulls[12] = false;
+
+	values[13] = TransactionIdGetDatum(ControlFile->checkPointCopy.oldestActiveXid);
+	nulls[13] = false;
+
+	values[14] = TransactionIdGetDatum(ControlFile->checkPointCopy.oldestMulti);
+	nulls[14] = false;
+
+	values[15] = ObjectIdGetDatum(ControlFile->checkPointCopy.oldestMultiDB);
+	nulls[15] = false;
+
+	values[16] = TransactionIdGetDatum(ControlFile->checkPointCopy.oldestCommitTsXid);
+	nulls[16] = false;
+
+	values[17] = TransactionIdGetDatum(ControlFile->checkPointCopy.newestCommitTsXid);
+	nulls[17] = false;
+
+	values[18] = TimestampTzGetDatum(
+					time_t_to_timestamptz(ControlFile->checkPointCopy.time));
+	nulls[18] = false;
+
+	htup = heap_form_tuple(tupdesc, values, nulls);
+
+	PG_RETURN_DATUM(HeapTupleGetDatum(htup));
+}
+
+Datum
+pg_control_recovery(PG_FUNCTION_ARGS)
+{
+	Datum				values[5];
+	bool				nulls[5];
+	TupleDesc			tupdesc;
+	HeapTuple			htup;
+	ControlFileData	   *ControlFile;
+
+	/*
+	 * Construct a tuple descriptor for the result row.  This must match this
+	 * function's pg_proc entry!
+	 */
+	tupdesc = CreateTemplateTupleDesc(5, false);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 1, "min_recovery_end_location",
+					   LSNOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 2, "min_recovery_end_timeline",
+					   INT4OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 3, "backup_start_location",
+					   LSNOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 4, "backup_end_location",
+					   LSNOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 5, "end_of_backup_record_required",
+					   BOOLOID, -1, 0);
+	tupdesc = BlessTupleDesc(tupdesc);
+
+	/* read the control file */
+	ControlFile = get_controlfile(DataDir, NULL);
+
+	values[0] = LSNGetDatum(ControlFile->minRecoveryPoint);
+	nulls[0] = false;
+
+	values[1] = Int32GetDatum(ControlFile->minRecoveryPointTLI);
+	nulls[1] = false;
+
+	values[2] = LSNGetDatum(ControlFile->backupStartPoint);
+	nulls[2] = false;
+
+	values[3] = LSNGetDatum(ControlFile->backupEndPoint);
+	nulls[3] = false;
+
+	values[4] = BoolGetDatum(ControlFile->backupEndRequired);
+	nulls[4] = false;
+
+	htup = heap_form_tuple(tupdesc, values, nulls);
+
+	PG_RETURN_DATUM(HeapTupleGetDatum(htup));
+}
+
+Datum
+pg_control_init(PG_FUNCTION_ARGS)
+{
+	Datum				values[13];
+	bool				nulls[13];
+	TupleDesc			tupdesc;
+	HeapTuple			htup;
+	ControlFileData	   *ControlFile;
+
+	/*
+	 * Construct a tuple descriptor for the result row.  This must match this
+	 * function's pg_proc entry!
+	 */
+	tupdesc = CreateTemplateTupleDesc(13, false);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 1, "max_data_alignment",
+					   INT4OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 2, "database_block_size",
+					   INT4OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 3, "blocks_per_segment",
+					   INT4OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 4, "wal_block_size",
+					   INT4OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 5, "bytes_per_wal_segment",
+					   INT4OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 6, "max_identifier_length",
+					   INT4OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 7, "max_index_columns",
+					   INT4OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 8, "max_toast_chunk_size",
+					   INT4OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 9, "large_object_chunk_size",
+					   INT4OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 10, "bigint_timestamps",
+					   BOOLOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 11, "float4_pass_by_value",
+					   BOOLOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 12, "float8_pass_by_value",
+					   BOOLOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 13, "data_page_checksum_version",
+					   INT4OID, -1, 0);
+	tupdesc = BlessTupleDesc(tupdesc);
+
+	/* read the control file */
+	ControlFile = get_controlfile(DataDir, NULL);
+
+	values[0] = Int32GetDatum(ControlFile->maxAlign);
+	nulls[0] = false;
+
+	values[1] = Int32GetDatum(ControlFile->blcksz);
+	nulls[1] = false;
+
+	values[2] = Int32GetDatum(ControlFile->relseg_size);
+	nulls[2] = false;
+
+	values[3] = Int32GetDatum(ControlFile->xlog_blcksz);
+	nulls[3] = false;
+
+	values[4] = Int32GetDatum(ControlFile->xlog_seg_size);
+	nulls[4] = false;
+
+	values[5] = Int32GetDatum(ControlFile->nameDataLen);
+	nulls[5] = false;
+
+	values[6] = Int32GetDatum(ControlFile->indexMaxKeys);
+	nulls[6] = false;
+
+	values[7] = Int32GetDatum(ControlFile->toast_max_chunk_size);
+	nulls[7] = false;
+
+	values[8] = Int32GetDatum(ControlFile->loblksize);
+	nulls[8] = false;
+
+	values[9] = BoolGetDatum(ControlFile->enableIntTimes);
+	nulls[9] = false;
+
+	values[10] = BoolGetDatum(ControlFile->float4ByVal);
+	nulls[10] = false;
+
+	values[11] = BoolGetDatum(ControlFile->float8ByVal);
+	nulls[11] = false;
+
+	values[12] = Int32GetDatum(ControlFile->data_checksum_version);
+	nulls[12] = false;
+
+	htup = heap_form_tuple(tupdesc, values, nulls);
+
+	PG_RETURN_DATUM(HeapTupleGetDatum(htup));
+}