!2458 issue修复：memcheck编译下gist索引构建内存泄漏修复

Merge pull request !2458 from zhangzhixian/gist_index_memory_leak_fix

src/gausskernel/storage/access/gist/gistbuild.cpp

@@ -882,8 +882,11 @@ static void gistProcessEmptyingQueue(GISTBuildState *buildstate)
                 break;
             }
 
-            /* Free all the memory allocated during index tuple processing */
-            MemoryContextReset(buildstate->giststate->tempCxt);
+            /*
+             * MemoryContextReset will be called by caller, or caller of caller (for example, gistBuildCallback).
+             * Just reset after all utilities of relative pointers in buildstate->giststate->tempCxt is finished
+             * in case of memory leak.
+             */
         }
     }
 }
@@ -936,6 +939,7 @@ static void gistEmptyAllBuffers(GISTBuildState *buildstate)
         ereport(DEBUG2, (errmsg("emptied all buffers at level %d", i)));
     }
     (void)MemoryContextSwitchTo(oldCtx);
+    MemoryContextReset(buildstate->giststate->tempCxt);
 }
 
 /*

src/test/regress/expected/create_index_gist.out

@@ -501,6 +501,10 @@ SELECT * FROM point_tbl WHERE f1 <@ '(-10,-10),(10,10)':: box ORDER BY f1 <-> '0
  (10,10)
 (4 rows)
 
+-- test for gist index building when buffering=on
+create table t(id int, c_point point);
+insert into t select id, point'(1, 2)' from (select * from generate_series(1, 200000) as id) as x;
+create index i on t using gist(c_point) with (buffering=on);
 
 RESET enable_seqscan;
 RESET enable_indexscan;

src/test/regress/sql/create_index_gist.sql

@@ -181,6 +181,11 @@ EXPLAIN (NUM_NODES OFF, NODES OFF, COSTS OFF)
 SELECT * FROM point_tbl WHERE f1 <@ '(-10,-10),(10,10)':: box ORDER BY f1 <-> '0,1';
 SELECT * FROM point_tbl WHERE f1 <@ '(-10,-10),(10,10)':: box ORDER BY f1 <-> '0,1';
 
+-- test for gist index building when buffering=on
+create table t(id int, c_point point);
+insert into t select id, point'(1, 2)' from (select * from generate_series(1, 200000) as id) as x;
+create index i on t using gist(c_point) with (buffering=on);
+
 RESET enable_seqscan;
 RESET enable_indexscan;
 RESET enable_bitmapscan;