Refactor stats API and remove ptrack_get_change_file_stat

Author: ololobus

Diff for: README.md

@@ -67,7 +67,6 @@ To disable `ptrack` and clean up all remaining service files set `ptrack.map_siz
  * ptrack_init_lsn() — returns LSN of the last ptrack map initialization.
  * ptrack_get_pagemapset(start_lsn pg_lsn) — returns a set of changed data files with bitmaps of changed blocks since specified `start_lsn`.
  * ptrack_get_change_stat(start_lsn pg_lsn) — returns statistic of changes (number of files, pages and size in MB) since specified `start_lsn`.
- * ptrack_get_change_file_stat(start_lsn pg_lsn) — returns per file statistic of changes (number of pages and size in MB) since specified `start_lsn`.
 
 Usage example:
 

Diff for: ptrack--2.1--2.2.sql

@@ -3,10 +3,18 @@
 -- Complain if script is sourced in psql, rather than via ALTER EXTENSION
 \echo Use "ALTER EXTENSION ptrack UPDATE;" to load this file.\ quit
 
+DROP FUNCTION ptrack_get_pagemapset(start_lsn pg_lsn);
+CREATE FUNCTION ptrack_get_pagemapset(start_lsn pg_lsn)
+RETURNS TABLE (path			text,
+			   pagecount	bigint,
+			   pagemap		bytea)
+AS 'MODULE_PATHNAME'
+LANGUAGE C STRICT VOLATILE;
+
 CREATE FUNCTION ptrack_get_change_stat(start_lsn pg_lsn)
 	RETURNS TABLE (
 		files bigint,
-		pages bigint,
+		pages numeric,
 		"size, MB" numeric
 	) AS
 $func$
@@ -18,37 +26,10 @@ BEGIN
 	RETURN QUERY
 	SELECT changed_files,
 		   changed_pages,
-		   block_size*changed_pages/(1024.0*1024)
+		   block_size * changed_pages / (1024.0 * 1024)
 	FROM
 		(SELECT count(path) AS changed_files,
-				sum(
-					length(replace(right((pagemap)::text, -1)::varbit::text, '0', ''))
-				) AS changed_pages
+				sum(pagecount) AS changed_pages
 		 FROM ptrack_get_pagemapset(start_lsn)) s;
 END
 $func$ LANGUAGE plpgsql;
-
-CREATE FUNCTION ptrack_get_change_file_stat(start_lsn pg_lsn)
-	RETURNS TABLE (
-		file_path text,
-		pages int,
-		"size, MB" numeric
-	) AS
-$func$
-DECLARE
-block_size bigint;
-BEGIN
-	block_size := (SELECT setting FROM pg_settings WHERE name = 'block_size');
-
-	RETURN QUERY
-	SELECT s.path,
-		   changed_pages,
-		   block_size*changed_pages/(1024.0*1024)
-	FROM
-		(SELECT path,
-				length(replace(right((pagemap)::text, -1)::varbit::text, '0', ''))
-					AS changed_pages
-		 FROM ptrack_get_pagemapset(start_lsn)) s
-	ORDER BY (changed_pages, s.path) DESC;
-END
-$func$ LANGUAGE plpgsql;

Diff for: ptrack.c

@@ -424,6 +424,7 @@ ptrack_get_pagemapset(PG_FUNCTION_ARGS)
 	FuncCallContext *funcctx;
 	MemoryContext oldcontext;
 	datapagemap_t pagemap;
+	int64		pagecount = 0;
 	char		gather_path[MAXPGPATH];
 
 	/* Exit immediately if there is no map */
@@ -444,12 +445,13 @@ ptrack_get_pagemapset(PG_FUNCTION_ARGS)
 
 		/* Make tuple descriptor */
 #if PG_VERSION_NUM >= 120000
-		tupdesc = CreateTemplateTupleDesc(2);
+		tupdesc = CreateTemplateTupleDesc(3);
 #else
-		tupdesc = CreateTemplateTupleDesc(2, false);
+		tupdesc = CreateTemplateTupleDesc(3, false);
 #endif
 		TupleDescInitEntry(tupdesc, (AttrNumber) 1, "path", TEXTOID, -1, 0);
-		TupleDescInitEntry(tupdesc, (AttrNumber) 2, "pagemap", BYTEAOID, -1, 0);
+		TupleDescInitEntry(tupdesc, (AttrNumber) 2, "pagecount", INT8OID, -1, 0);
+		TupleDescInitEntry(tupdesc, (AttrNumber) 3, "pagemap", BYTEAOID, -1, 0);
 		funcctx->tuple_desc = BlessTupleDesc(tupdesc);
 
 		funcctx->user_fctx = ctx;
@@ -497,8 +499,8 @@ ptrack_get_pagemapset(PG_FUNCTION_ARGS)
 			/* We completed a segment and there is a bitmap to return */
 			if (pagemap.bitmap != NULL)
 			{
-				Datum		values[2];
-				bool		nulls[2] = {false};
+				Datum		values[3];
+				bool		nulls[3] = {false};
 				char		pathname[MAXPGPATH];
 				bytea	   *result = NULL;
 				Size		result_sz = pagemap.bitmapsize + VARHDRSZ;
@@ -512,11 +514,13 @@ ptrack_get_pagemapset(PG_FUNCTION_ARGS)
 				strcpy(pathname, ctx->relpath);
 
 				values[0] = CStringGetTextDatum(pathname);
-				values[1] = PointerGetDatum(result);
+				values[1] = Int64GetDatum(pagecount);
+				values[2] = PointerGetDatum(result);
 
 				pfree(pagemap.bitmap);
 				pagemap.bitmap = NULL;
 				pagemap.bitmapsize = 0;
+				pagecount = 0;
 
 				htup = heap_form_tuple(funcctx->tuple_desc, values, nulls);
 				if (htup)
@@ -553,7 +557,10 @@ ptrack_get_pagemapset(PG_FUNCTION_ARGS)
 
 			/* Block has been changed since specified LSN.  Mark it in the bitmap */
 			if (update_lsn2 >= ctx->lsn)
+			{
+				pagecount += 1;
 				datapagemap_add(&pagemap, ctx->bid.blocknum % ((BlockNumber) RELSEG_SIZE));
+			}
 		}
 
 		ctx->bid.blocknum += 1;

Diff for: t/001_basic.pl

@@ -10,7 +10,7 @@
 use TestLib;
 use Test::More;
 
-plan tests => 25;
+plan tests => 24;
 
 my $node;
 my $res;
@@ -119,9 +119,6 @@
 $res_stdout = $node->safe_psql("postgres", "SELECT pages FROM ptrack_get_change_stat('$flush_lsn')");
 is($res_stdout > 0, 1, 'should be able to get aggregated stats of changes');
 
-$res_stdout = $node->safe_psql("postgres", "SELECT count(*) FROM ptrack_get_change_file_stat('$flush_lsn')");
-is($res_stdout > 0, 1, 'should be able to get per file stats of changes');
-
 # We should be able to change ptrack map size (but loose all changes)
 $node->append_conf(
 	'postgresql.conf', q{