Adding upstream version 16.2.upstream/16.2

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1022 insertions, 0 deletions

diff --git a/src/backend/utils/adt/dbsize.c b/src/backend/utils/adt/dbsize.c
new file mode 100644
index 0000000..e5c0f1c
--- /dev/null
+++ b/src/backend/utils/adt/dbsize.c
@@ -0,0 +1,1022 @@
+/*
+ * dbsize.c
+ *		Database object size functions, and related inquiries
+ *
+ * Copyright (c) 2002-2023, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  src/backend/utils/adt/dbsize.c
+ *
+ */
+
+#include "postgres.h"
+
+#include <sys/stat.h>
+
+#include "access/htup_details.h"
+#include "access/relation.h"
+#include "catalog/catalog.h"
+#include "catalog/namespace.h"
+#include "catalog/pg_authid.h"
+#include "catalog/pg_database.h"
+#include "catalog/pg_tablespace.h"
+#include "commands/dbcommands.h"
+#include "commands/tablespace.h"
+#include "miscadmin.h"
+#include "storage/fd.h"
+#include "utils/acl.h"
+#include "utils/builtins.h"
+#include "utils/numeric.h"
+#include "utils/rel.h"
+#include "utils/relfilenumbermap.h"
+#include "utils/relmapper.h"
+#include "utils/syscache.h"
+
+/* Divide by two and round away from zero */
+#define half_rounded(x)   (((x) + ((x) < 0 ? -1 : 1)) / 2)
+
+/* Units used in pg_size_pretty functions.  All units must be powers of 2 */
+struct size_pretty_unit
+{
+	const char *name;			/* bytes, kB, MB, GB etc */
+	uint32		limit;			/* upper limit, prior to half rounding after
+								 * converting to this unit. */
+	bool		round;			/* do half rounding for this unit */
+	uint8		unitbits;		/* (1 << unitbits) bytes to make 1 of this
+								 * unit */
+};
+
+/* When adding units here also update the docs and the error message in pg_size_bytes */
+static const struct size_pretty_unit size_pretty_units[] = {
+	{"bytes", 10 * 1024, false, 0},
+	{"kB", 20 * 1024 - 1, true, 10},
+	{"MB", 20 * 1024 - 1, true, 20},
+	{"GB", 20 * 1024 - 1, true, 30},
+	{"TB", 20 * 1024 - 1, true, 40},
+	{"PB", 20 * 1024 - 1, true, 50},
+	{NULL, 0, false, 0}
+};
+
+/* Additional unit aliases accepted by pg_size_bytes */
+struct size_bytes_unit_alias
+{
+	const char *alias;
+	int			unit_index;		/* corresponding size_pretty_units element */
+};
+
+/* When adding units here also update the docs and the error message in pg_size_bytes */
+static const struct size_bytes_unit_alias size_bytes_aliases[] = {
+	{"B", 0},
+	{NULL}
+};
+
+/* Return physical size of directory contents, or 0 if dir doesn't exist */
+static int64
+db_dir_size(const char *path)
+{
+	int64		dirsize = 0;
+	struct dirent *direntry;
+	DIR		   *dirdesc;
+	char		filename[MAXPGPATH * 2];
+
+	dirdesc = AllocateDir(path);
+
+	if (!dirdesc)
+		return 0;
+
+	while ((direntry = ReadDir(dirdesc, path)) != NULL)
+	{
+		struct stat fst;
+
+		CHECK_FOR_INTERRUPTS();
+
+		if (strcmp(direntry->d_name, ".") == 0 ||
+			strcmp(direntry->d_name, "..") == 0)
+			continue;
+
+		snprintf(filename, sizeof(filename), "%s/%s", path, direntry->d_name);
+
+		if (stat(filename, &fst) < 0)
+		{
+			if (errno == ENOENT)
+				continue;
+			else
+				ereport(ERROR,
+						(errcode_for_file_access(),
+						 errmsg("could not stat file \"%s\": %m", filename)));
+		}
+		dirsize += fst.st_size;
+	}
+
+	FreeDir(dirdesc);
+	return dirsize;
+}
+
+/*
+ * calculate size of database in all tablespaces
+ */
+static int64
+calculate_database_size(Oid dbOid)
+{
+	int64		totalsize;
+	DIR		   *dirdesc;
+	struct dirent *direntry;
+	char		dirpath[MAXPGPATH];
+	char		pathname[MAXPGPATH + 21 + sizeof(TABLESPACE_VERSION_DIRECTORY)];
+	AclResult	aclresult;
+
+	/*
+	 * User must have connect privilege for target database or have privileges
+	 * of pg_read_all_stats
+	 */
+	aclresult = object_aclcheck(DatabaseRelationId, dbOid, GetUserId(), ACL_CONNECT);
+	if (aclresult != ACLCHECK_OK &&
+		!has_privs_of_role(GetUserId(), ROLE_PG_READ_ALL_STATS))
+	{
+		aclcheck_error(aclresult, OBJECT_DATABASE,
+					   get_database_name(dbOid));
+	}
+
+	/* Shared storage in pg_global is not counted */
+
+	/* Include pg_default storage */
+	snprintf(pathname, sizeof(pathname), "base/%u", dbOid);
+	totalsize = db_dir_size(pathname);
+
+	/* Scan the non-default tablespaces */
+	snprintf(dirpath, MAXPGPATH, "pg_tblspc");
+	dirdesc = AllocateDir(dirpath);
+
+	while ((direntry = ReadDir(dirdesc, dirpath)) != NULL)
+	{
+		CHECK_FOR_INTERRUPTS();
+
+		if (strcmp(direntry->d_name, ".") == 0 ||
+			strcmp(direntry->d_name, "..") == 0)
+			continue;
+
+		snprintf(pathname, sizeof(pathname), "pg_tblspc/%s/%s/%u",
+				 direntry->d_name, TABLESPACE_VERSION_DIRECTORY, dbOid);
+		totalsize += db_dir_size(pathname);
+	}
+
+	FreeDir(dirdesc);
+
+	return totalsize;
+}
+
+Datum
+pg_database_size_oid(PG_FUNCTION_ARGS)
+{
+	Oid			dbOid = PG_GETARG_OID(0);
+	int64		size;
+
+	size = calculate_database_size(dbOid);
+
+	if (size == 0)
+		PG_RETURN_NULL();
+
+	PG_RETURN_INT64(size);
+}
+
+Datum
+pg_database_size_name(PG_FUNCTION_ARGS)
+{
+	Name		dbName = PG_GETARG_NAME(0);
+	Oid			dbOid = get_database_oid(NameStr(*dbName), false);
+	int64		size;
+
+	size = calculate_database_size(dbOid);
+
+	if (size == 0)
+		PG_RETURN_NULL();
+
+	PG_RETURN_INT64(size);
+}
+
+
+/*
+ * Calculate total size of tablespace. Returns -1 if the tablespace directory
+ * cannot be found.
+ */
+static int64
+calculate_tablespace_size(Oid tblspcOid)
+{
+	char		tblspcPath[MAXPGPATH];
+	char		pathname[MAXPGPATH * 2];
+	int64		totalsize = 0;
+	DIR		   *dirdesc;
+	struct dirent *direntry;
+	AclResult	aclresult;
+
+	/*
+	 * User must have privileges of pg_read_all_stats or have CREATE privilege
+	 * for target tablespace, either explicitly granted or implicitly because
+	 * it is default for current database.
+	 */
+	if (tblspcOid != MyDatabaseTableSpace &&
+		!has_privs_of_role(GetUserId(), ROLE_PG_READ_ALL_STATS))
+	{
+		aclresult = object_aclcheck(TableSpaceRelationId, tblspcOid, GetUserId(), ACL_CREATE);
+		if (aclresult != ACLCHECK_OK)
+			aclcheck_error(aclresult, OBJECT_TABLESPACE,
+						   get_tablespace_name(tblspcOid));
+	}
+
+	if (tblspcOid == DEFAULTTABLESPACE_OID)
+		snprintf(tblspcPath, MAXPGPATH, "base");
+	else if (tblspcOid == GLOBALTABLESPACE_OID)
+		snprintf(tblspcPath, MAXPGPATH, "global");
+	else
+		snprintf(tblspcPath, MAXPGPATH, "pg_tblspc/%u/%s", tblspcOid,
+				 TABLESPACE_VERSION_DIRECTORY);
+
+	dirdesc = AllocateDir(tblspcPath);
+
+	if (!dirdesc)
+		return -1;
+
+	while ((direntry = ReadDir(dirdesc, tblspcPath)) != NULL)
+	{
+		struct stat fst;
+
+		CHECK_FOR_INTERRUPTS();
+
+		if (strcmp(direntry->d_name, ".") == 0 ||
+			strcmp(direntry->d_name, "..") == 0)
+			continue;
+
+		snprintf(pathname, sizeof(pathname), "%s/%s", tblspcPath, direntry->d_name);
+
+		if (stat(pathname, &fst) < 0)
+		{
+			if (errno == ENOENT)
+				continue;
+			else
+				ereport(ERROR,
+						(errcode_for_file_access(),
+						 errmsg("could not stat file \"%s\": %m", pathname)));
+		}
+
+		if (S_ISDIR(fst.st_mode))
+			totalsize += db_dir_size(pathname);
+
+		totalsize += fst.st_size;
+	}
+
+	FreeDir(dirdesc);
+
+	return totalsize;
+}
+
+Datum
+pg_tablespace_size_oid(PG_FUNCTION_ARGS)
+{
+	Oid			tblspcOid = PG_GETARG_OID(0);
+	int64		size;
+
+	size = calculate_tablespace_size(tblspcOid);
+
+	if (size < 0)
+		PG_RETURN_NULL();
+
+	PG_RETURN_INT64(size);
+}
+
+Datum
+pg_tablespace_size_name(PG_FUNCTION_ARGS)
+{
+	Name		tblspcName = PG_GETARG_NAME(0);
+	Oid			tblspcOid = get_tablespace_oid(NameStr(*tblspcName), false);
+	int64		size;
+
+	size = calculate_tablespace_size(tblspcOid);
+
+	if (size < 0)
+		PG_RETURN_NULL();
+
+	PG_RETURN_INT64(size);
+}
+
+
+/*
+ * calculate size of (one fork of) a relation
+ *
+ * Note: we can safely apply this to temp tables of other sessions, so there
+ * is no check here or at the call sites for that.
+ */
+static int64
+calculate_relation_size(RelFileLocator *rfn, BackendId backend, ForkNumber forknum)
+{
+	int64		totalsize = 0;
+	char	   *relationpath;
+	char		pathname[MAXPGPATH];
+	unsigned int segcount = 0;
+
+	relationpath = relpathbackend(*rfn, backend, forknum);
+
+	for (segcount = 0;; segcount++)
+	{
+		struct stat fst;
+
+		CHECK_FOR_INTERRUPTS();
+
+		if (segcount == 0)
+			snprintf(pathname, MAXPGPATH, "%s",
+					 relationpath);
+		else
+			snprintf(pathname, MAXPGPATH, "%s.%u",
+					 relationpath, segcount);
+
+		if (stat(pathname, &fst) < 0)
+		{
+			if (errno == ENOENT)
+				break;
+			else
+				ereport(ERROR,
+						(errcode_for_file_access(),
+						 errmsg("could not stat file \"%s\": %m", pathname)));
+		}
+		totalsize += fst.st_size;
+	}
+
+	return totalsize;
+}
+
+Datum
+pg_relation_size(PG_FUNCTION_ARGS)
+{
+	Oid			relOid = PG_GETARG_OID(0);
+	text	   *forkName = PG_GETARG_TEXT_PP(1);
+	Relation	rel;
+	int64		size;
+
+	rel = try_relation_open(relOid, AccessShareLock);
+
+	/*
+	 * Before 9.2, we used to throw an error if the relation didn't exist, but
+	 * that makes queries like "SELECT pg_relation_size(oid) FROM pg_class"
+	 * less robust, because while we scan pg_class with an MVCC snapshot,
+	 * someone else might drop the table. It's better to return NULL for
+	 * already-dropped tables than throw an error and abort the whole query.
+	 */
+	if (rel == NULL)
+		PG_RETURN_NULL();
+
+	size = calculate_relation_size(&(rel->rd_locator), rel->rd_backend,
+								   forkname_to_number(text_to_cstring(forkName)));
+
+	relation_close(rel, AccessShareLock);
+
+	PG_RETURN_INT64(size);
+}
+
+/*
+ * Calculate total on-disk size of a TOAST relation, including its indexes.
+ * Must not be applied to non-TOAST relations.
+ */
+static int64
+calculate_toast_table_size(Oid toastrelid)
+{
+	int64		size = 0;
+	Relation	toastRel;
+	ForkNumber	forkNum;
+	ListCell   *lc;
+	List	   *indexlist;
+
+	toastRel = relation_open(toastrelid, AccessShareLock);
+
+	/* toast heap size, including FSM and VM size */
+	for (forkNum = 0; forkNum <= MAX_FORKNUM; forkNum++)
+		size += calculate_relation_size(&(toastRel->rd_locator),
+										toastRel->rd_backend, forkNum);
+
+	/* toast index size, including FSM and VM size */
+	indexlist = RelationGetIndexList(toastRel);
+
+	/* Size is calculated using all the indexes available */
+	foreach(lc, indexlist)
+	{
+		Relation	toastIdxRel;
+
+		toastIdxRel = relation_open(lfirst_oid(lc),
+									AccessShareLock);
+		for (forkNum = 0; forkNum <= MAX_FORKNUM; forkNum++)
+			size += calculate_relation_size(&(toastIdxRel->rd_locator),
+											toastIdxRel->rd_backend, forkNum);
+
+		relation_close(toastIdxRel, AccessShareLock);
+	}
+	list_free(indexlist);
+	relation_close(toastRel, AccessShareLock);
+
+	return size;
+}
+
+/*
+ * Calculate total on-disk size of a given table,
+ * including FSM and VM, plus TOAST table if any.
+ * Indexes other than the TOAST table's index are not included.
+ *
+ * Note that this also behaves sanely if applied to an index or toast table;
+ * those won't have attached toast tables, but they can have multiple forks.
+ */
+static int64
+calculate_table_size(Relation rel)
+{
+	int64		size = 0;
+	ForkNumber	forkNum;
+
+	/*
+	 * heap size, including FSM and VM
+	 */
+	for (forkNum = 0; forkNum <= MAX_FORKNUM; forkNum++)
+		size += calculate_relation_size(&(rel->rd_locator), rel->rd_backend,
+										forkNum);
+
+	/*
+	 * Size of toast relation
+	 */
+	if (OidIsValid(rel->rd_rel->reltoastrelid))
+		size += calculate_toast_table_size(rel->rd_rel->reltoastrelid);
+
+	return size;
+}
+
+/*
+ * Calculate total on-disk size of all indexes attached to the given table.
+ *
+ * Can be applied safely to an index, but you'll just get zero.
+ */
+static int64
+calculate_indexes_size(Relation rel)
+{
+	int64		size = 0;
+
+	/*
+	 * Aggregate all indexes on the given relation
+	 */
+	if (rel->rd_rel->relhasindex)
+	{
+		List	   *index_oids = RelationGetIndexList(rel);
+		ListCell   *cell;
+
+		foreach(cell, index_oids)
+		{
+			Oid			idxOid = lfirst_oid(cell);
+			Relation	idxRel;
+			ForkNumber	forkNum;
+
+			idxRel = relation_open(idxOid, AccessShareLock);
+
+			for (forkNum = 0; forkNum <= MAX_FORKNUM; forkNum++)
+				size += calculate_relation_size(&(idxRel->rd_locator),
+												idxRel->rd_backend,
+												forkNum);
+
+			relation_close(idxRel, AccessShareLock);
+		}
+
+		list_free(index_oids);
+	}
+
+	return size;
+}
+
+Datum
+pg_table_size(PG_FUNCTION_ARGS)
+{
+	Oid			relOid = PG_GETARG_OID(0);
+	Relation	rel;
+	int64		size;
+
+	rel = try_relation_open(relOid, AccessShareLock);
+
+	if (rel == NULL)
+		PG_RETURN_NULL();
+
+	size = calculate_table_size(rel);
+
+	relation_close(rel, AccessShareLock);
+
+	PG_RETURN_INT64(size);
+}
+
+Datum
+pg_indexes_size(PG_FUNCTION_ARGS)
+{
+	Oid			relOid = PG_GETARG_OID(0);
+	Relation	rel;
+	int64		size;
+
+	rel = try_relation_open(relOid, AccessShareLock);
+
+	if (rel == NULL)
+		PG_RETURN_NULL();
+
+	size = calculate_indexes_size(rel);
+
+	relation_close(rel, AccessShareLock);
+
+	PG_RETURN_INT64(size);
+}
+
+/*
+ *	Compute the on-disk size of all files for the relation,
+ *	including heap data, index data, toast data, FSM, VM.
+ */
+static int64
+calculate_total_relation_size(Relation rel)
+{
+	int64		size;
+
+	/*
+	 * Aggregate the table size, this includes size of the heap, toast and
+	 * toast index with free space and visibility map
+	 */
+	size = calculate_table_size(rel);
+
+	/*
+	 * Add size of all attached indexes as well
+	 */
+	size += calculate_indexes_size(rel);
+
+	return size;
+}
+
+Datum
+pg_total_relation_size(PG_FUNCTION_ARGS)
+{
+	Oid			relOid = PG_GETARG_OID(0);
+	Relation	rel;
+	int64		size;
+
+	rel = try_relation_open(relOid, AccessShareLock);
+
+	if (rel == NULL)
+		PG_RETURN_NULL();
+
+	size = calculate_total_relation_size(rel);
+
+	relation_close(rel, AccessShareLock);
+
+	PG_RETURN_INT64(size);
+}
+
+/*
+ * formatting with size units
+ */
+Datum
+pg_size_pretty(PG_FUNCTION_ARGS)
+{
+	int64		size = PG_GETARG_INT64(0);
+	char		buf[64];
+	const struct size_pretty_unit *unit;
+
+	for (unit = size_pretty_units; unit->name != NULL; unit++)
+	{
+		uint8		bits;
+
+		/* use this unit if there are no more units or we're below the limit */
+		if (unit[1].name == NULL || i64abs(size) < unit->limit)
+		{
+			if (unit->round)
+				size = half_rounded(size);
+
+			snprintf(buf, sizeof(buf), INT64_FORMAT " %s", size, unit->name);
+			break;
+		}
+
+		/*
+		 * Determine the number of bits to use to build the divisor.  We may
+		 * need to use 1 bit less than the difference between this and the
+		 * next unit if the next unit uses half rounding.  Or we may need to
+		 * shift an extra bit if this unit uses half rounding and the next one
+		 * does not.  We use division rather than shifting right by this
+		 * number of bits to ensure positive and negative values are rounded
+		 * in the same way.
+		 */
+		bits = (unit[1].unitbits - unit->unitbits - (unit[1].round == true)
+				+ (unit->round == true));
+		size /= ((int64) 1) << bits;
+	}
+
+	PG_RETURN_TEXT_P(cstring_to_text(buf));
+}
+
+static char *
+numeric_to_cstring(Numeric n)
+{
+	Datum		d = NumericGetDatum(n);
+
+	return DatumGetCString(DirectFunctionCall1(numeric_out, d));
+}
+
+static bool
+numeric_is_less(Numeric a, Numeric b)
+{
+	Datum		da = NumericGetDatum(a);
+	Datum		db = NumericGetDatum(b);
+
+	return DatumGetBool(DirectFunctionCall2(numeric_lt, da, db));
+}
+
+static Numeric
+numeric_absolute(Numeric n)
+{
+	Datum		d = NumericGetDatum(n);
+	Datum		result;
+
+	result = DirectFunctionCall1(numeric_abs, d);
+	return DatumGetNumeric(result);
+}
+
+static Numeric
+numeric_half_rounded(Numeric n)
+{
+	Datum		d = NumericGetDatum(n);
+	Datum		zero;
+	Datum		one;
+	Datum		two;
+	Datum		result;
+
+	zero = NumericGetDatum(int64_to_numeric(0));
+	one = NumericGetDatum(int64_to_numeric(1));
+	two = NumericGetDatum(int64_to_numeric(2));
+
+	if (DatumGetBool(DirectFunctionCall2(numeric_ge, d, zero)))
+		d = DirectFunctionCall2(numeric_add, d, one);
+	else
+		d = DirectFunctionCall2(numeric_sub, d, one);
+
+	result = DirectFunctionCall2(numeric_div_trunc, d, two);
+	return DatumGetNumeric(result);
+}
+
+static Numeric
+numeric_truncated_divide(Numeric n, int64 divisor)
+{
+	Datum		d = NumericGetDatum(n);
+	Datum		divisor_numeric;
+	Datum		result;
+
+	divisor_numeric = NumericGetDatum(int64_to_numeric(divisor));
+	result = DirectFunctionCall2(numeric_div_trunc, d, divisor_numeric);
+	return DatumGetNumeric(result);
+}
+
+Datum
+pg_size_pretty_numeric(PG_FUNCTION_ARGS)
+{
+	Numeric		size = PG_GETARG_NUMERIC(0);
+	char	   *result = NULL;
+	const struct size_pretty_unit *unit;
+
+	for (unit = size_pretty_units; unit->name != NULL; unit++)
+	{
+		unsigned int shiftby;
+
+		/* use this unit if there are no more units or we're below the limit */
+		if (unit[1].name == NULL ||
+			numeric_is_less(numeric_absolute(size),
+							int64_to_numeric(unit->limit)))
+		{
+			if (unit->round)
+				size = numeric_half_rounded(size);
+
+			result = psprintf("%s %s", numeric_to_cstring(size), unit->name);
+			break;
+		}
+
+		/*
+		 * Determine the number of bits to use to build the divisor.  We may
+		 * need to use 1 bit less than the difference between this and the
+		 * next unit if the next unit uses half rounding.  Or we may need to
+		 * shift an extra bit if this unit uses half rounding and the next one
+		 * does not.
+		 */
+		shiftby = (unit[1].unitbits - unit->unitbits - (unit[1].round == true)
+				   + (unit->round == true));
+		size = numeric_truncated_divide(size, ((int64) 1) << shiftby);
+	}
+
+	PG_RETURN_TEXT_P(cstring_to_text(result));
+}
+
+/*
+ * Convert a human-readable size to a size in bytes
+ */
+Datum
+pg_size_bytes(PG_FUNCTION_ARGS)
+{
+	text	   *arg = PG_GETARG_TEXT_PP(0);
+	char	   *str,
+			   *strptr,
+			   *endptr;
+	char		saved_char;
+	Numeric		num;
+	int64		result;
+	bool		have_digits = false;
+
+	str = text_to_cstring(arg);
+
+	/* Skip leading whitespace */
+	strptr = str;
+	while (isspace((unsigned char) *strptr))
+		strptr++;
+
+	/* Check that we have a valid number and determine where it ends */
+	endptr = strptr;
+
+	/* Part (1): sign */
+	if (*endptr == '-' || *endptr == '+')
+		endptr++;
+
+	/* Part (2): main digit string */
+	if (isdigit((unsigned char) *endptr))
+	{
+		have_digits = true;
+		do
+			endptr++;
+		while (isdigit((unsigned char) *endptr));
+	}
+
+	/* Part (3): optional decimal point and fractional digits */
+	if (*endptr == '.')
+	{
+		endptr++;
+		if (isdigit((unsigned char) *endptr))
+		{
+			have_digits = true;
+			do
+				endptr++;
+			while (isdigit((unsigned char) *endptr));
+		}
+	}
+
+	/* Complain if we don't have a valid number at this point */
+	if (!have_digits)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("invalid size: \"%s\"", str)));
+
+	/* Part (4): optional exponent */
+	if (*endptr == 'e' || *endptr == 'E')
+	{
+		long		exponent;
+		char	   *cp;
+
+		/*
+		 * Note we might one day support EB units, so if what follows 'E'
+		 * isn't a number, just treat it all as a unit to be parsed.
+		 */
+		exponent = strtol(endptr + 1, &cp, 10);
+		(void) exponent;		/* Silence -Wunused-result warnings */
+		if (cp > endptr + 1)
+			endptr = cp;
+	}
+
+	/*
+	 * Parse the number, saving the next character, which may be the first
+	 * character of the unit string.
+	 */
+	saved_char = *endptr;
+	*endptr = '\0';
+
+	num = DatumGetNumeric(DirectFunctionCall3(numeric_in,
+											  CStringGetDatum(strptr),
+											  ObjectIdGetDatum(InvalidOid),
+											  Int32GetDatum(-1)));
+
+	*endptr = saved_char;
+
+	/* Skip whitespace between number and unit */
+	strptr = endptr;
+	while (isspace((unsigned char) *strptr))
+		strptr++;
+
+	/* Handle possible unit */
+	if (*strptr != '\0')
+	{
+		const struct size_pretty_unit *unit;
+		int64		multiplier = 0;
+
+		/* Trim any trailing whitespace */
+		endptr = str + VARSIZE_ANY_EXHDR(arg) - 1;
+
+		while (isspace((unsigned char) *endptr))
+			endptr--;
+
+		endptr++;
+		*endptr = '\0';
+
+		for (unit = size_pretty_units; unit->name != NULL; unit++)
+		{
+			/* Parse the unit case-insensitively */
+			if (pg_strcasecmp(strptr, unit->name) == 0)
+				break;
+		}
+
+		/* If not found, look in table of aliases */
+		if (unit->name == NULL)
+		{
+			for (const struct size_bytes_unit_alias *a = size_bytes_aliases; a->alias != NULL; a++)
+			{
+				if (pg_strcasecmp(strptr, a->alias) == 0)
+				{
+					unit = &size_pretty_units[a->unit_index];
+					break;
+				}
+			}
+		}
+
+		/* Verify we found a valid unit in the loop above */
+		if (unit->name == NULL)
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+					 errmsg("invalid size: \"%s\"", text_to_cstring(arg)),
+					 errdetail("Invalid size unit: \"%s\".", strptr),
+					 errhint("Valid units are \"bytes\", \"B\", \"kB\", \"MB\", \"GB\", \"TB\", and \"PB\".")));
+
+		multiplier = ((int64) 1) << unit->unitbits;
+
+		if (multiplier > 1)
+		{
+			Numeric		mul_num;
+
+			mul_num = int64_to_numeric(multiplier);
+
+			num = DatumGetNumeric(DirectFunctionCall2(numeric_mul,
+													  NumericGetDatum(mul_num),
+													  NumericGetDatum(num)));
+		}
+	}
+
+	result = DatumGetInt64(DirectFunctionCall1(numeric_int8,
+											   NumericGetDatum(num)));
+
+	PG_RETURN_INT64(result);
+}
+
+/*
+ * Get the filenode of a relation
+ *
+ * This is expected to be used in queries like
+ *		SELECT pg_relation_filenode(oid) FROM pg_class;
+ * That leads to a couple of choices.  We work from the pg_class row alone
+ * rather than actually opening each relation, for efficiency.  We don't
+ * fail if we can't find the relation --- some rows might be visible in
+ * the query's MVCC snapshot even though the relations have been dropped.
+ * (Note: we could avoid using the catcache, but there's little point
+ * because the relation mapper also works "in the now".)  We also don't
+ * fail if the relation doesn't have storage.  In all these cases it
+ * seems better to quietly return NULL.
+ */
+Datum
+pg_relation_filenode(PG_FUNCTION_ARGS)
+{
+	Oid			relid = PG_GETARG_OID(0);
+	RelFileNumber result;
+	HeapTuple	tuple;
+	Form_pg_class relform;
+
+	tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
+	if (!HeapTupleIsValid(tuple))
+		PG_RETURN_NULL();
+	relform = (Form_pg_class) GETSTRUCT(tuple);
+
+	if (RELKIND_HAS_STORAGE(relform->relkind))
+	{
+		if (relform->relfilenode)
+			result = relform->relfilenode;
+		else					/* Consult the relation mapper */
+			result = RelationMapOidToFilenumber(relid,
+												relform->relisshared);
+	}
+	else
+	{
+		/* no storage, return NULL */
+		result = InvalidRelFileNumber;
+	}
+
+	ReleaseSysCache(tuple);
+
+	if (!RelFileNumberIsValid(result))
+		PG_RETURN_NULL();
+
+	PG_RETURN_OID(result);
+}
+
+/*
+ * Get the relation via (reltablespace, relfilenumber)
+ *
+ * This is expected to be used when somebody wants to match an individual file
+ * on the filesystem back to its table. That's not trivially possible via
+ * pg_class, because that doesn't contain the relfilenumbers of shared and nailed
+ * tables.
+ *
+ * We don't fail but return NULL if we cannot find a mapping.
+ *
+ * InvalidOid can be passed instead of the current database's default
+ * tablespace.
+ */
+Datum
+pg_filenode_relation(PG_FUNCTION_ARGS)
+{
+	Oid			reltablespace = PG_GETARG_OID(0);
+	RelFileNumber relfilenumber = PG_GETARG_OID(1);
+	Oid			heaprel;
+
+	/* test needed so RelidByRelfilenumber doesn't misbehave */
+	if (!RelFileNumberIsValid(relfilenumber))
+		PG_RETURN_NULL();
+
+	heaprel = RelidByRelfilenumber(reltablespace, relfilenumber);
+
+	if (!OidIsValid(heaprel))
+		PG_RETURN_NULL();
+	else
+		PG_RETURN_OID(heaprel);
+}
+
+/*
+ * Get the pathname (relative to $PGDATA) of a relation
+ *
+ * See comments for pg_relation_filenode.
+ */
+Datum
+pg_relation_filepath(PG_FUNCTION_ARGS)
+{
+	Oid			relid = PG_GETARG_OID(0);
+	HeapTuple	tuple;
+	Form_pg_class relform;
+	RelFileLocator rlocator;
+	BackendId	backend;
+	char	   *path;
+
+	tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
+	if (!HeapTupleIsValid(tuple))
+		PG_RETURN_NULL();
+	relform = (Form_pg_class) GETSTRUCT(tuple);
+
+	if (RELKIND_HAS_STORAGE(relform->relkind))
+	{
+		/* This logic should match RelationInitPhysicalAddr */
+		if (relform->reltablespace)
+			rlocator.spcOid = relform->reltablespace;
+		else
+			rlocator.spcOid = MyDatabaseTableSpace;
+		if (rlocator.spcOid == GLOBALTABLESPACE_OID)
+			rlocator.dbOid = InvalidOid;
+		else
+			rlocator.dbOid = MyDatabaseId;
+		if (relform->relfilenode)
+			rlocator.relNumber = relform->relfilenode;
+		else					/* Consult the relation mapper */
+			rlocator.relNumber = RelationMapOidToFilenumber(relid,
+															relform->relisshared);
+	}
+	else
+	{
+		/* no storage, return NULL */
+		rlocator.relNumber = InvalidRelFileNumber;
+		/* some compilers generate warnings without these next two lines */
+		rlocator.dbOid = InvalidOid;
+		rlocator.spcOid = InvalidOid;
+	}
+
+	if (!RelFileNumberIsValid(rlocator.relNumber))
+	{
+		ReleaseSysCache(tuple);
+		PG_RETURN_NULL();
+	}
+
+	/* Determine owning backend. */
+	switch (relform->relpersistence)
+	{
+		case RELPERSISTENCE_UNLOGGED:
+		case RELPERSISTENCE_PERMANENT:
+			backend = InvalidBackendId;
+			break;
+		case RELPERSISTENCE_TEMP:
+			if (isTempOrTempToastNamespace(relform->relnamespace))
+				backend = BackendIdForTempRelations();
+			else
+			{
+				/* Do it the hard way. */
+				backend = GetTempNamespaceBackendId(relform->relnamespace);
+				Assert(backend != InvalidBackendId);
+			}
+			break;
+		default:
+			elog(ERROR, "invalid relpersistence: %c", relform->relpersistence);
+			backend = InvalidBackendId; /* placate compiler */
+			break;
+	}
+
+	ReleaseSysCache(tuple);
+
+	path = relpathbackend(rlocator, backend, MAIN_FORKNUM);
+
+	PG_RETURN_TEXT_P(cstring_to_text(path));
+}