Greenplum Segment Panic (SIGSEGV) during CREATE TABLE AS (CTAS) Operations with GPORCA

Products

• VMware Tanzu Greenplum
• VMware Tanzu Greenplum / Gemfire

Issue/Introduction

Users executing complex CREATE TABLE AS SELECT (CTAS) statements in Greenplum 7.x may encounter a cluster-wide segment panic. The database logs typically show:

• LOG: server process was terminated by signal 11: Segmentation fault
• PANIC: Unexpected internal error: Segment process received signal SIGSEGV

Segment log may show a stack trace like:

2026-07-03 10:45:33.036605 CEST,,,p655994,th0,,,2026-07-03 10:45:10 CEST,0,con107135,cmd176,seg15,,,,,"PANIC","XX000","Unexpected internal error: Segment process received signal SIGSEGV",,,,,,,0,,,,"1    0x7f071575b990 libpthread.so.0 <symbol not found> + 0x1575b990
2    0x99357c postgres slot_getsomeattrs_int (discriminator 5)
3    0x97dfe7 postgres <symbol not found> (execExprInterp.c:452)
4    0x9bc217 postgres <symbol not found> (palloc.h:194)
5    0x98c2c7 postgres <symbol not found> (execProcnode.c:646)
6    0x982f6b postgres <symbol not found> (execMain.c:2680)
7    0x983907 postgres standard_ExecutorRun (execMain.c:978)
8    0x983b05 postgres ExecutorRun (execMain.c:793)
9    0xba4c52 postgres <symbol not found> (pquery.c:252)
10   0xba517b postgres <symbol not found> (pquery.c:1525)
11   0xba6330 postgres PortalRun (pquery.c:1022)
12   0xb9f0e6 postgres <symbol not found> (postgres.c:1469)
"

This usually occurs on queries involving:

• UNION ALL constructs.
• CTE expressions.

Environment

Greenplum: 7.x

Cause

Greenplum 7.0.0 introduced a new feature to push down "JOIN" below "UNION ALL" which can improve performance in some cases. This is disabled by default by the GUC, optimizer_enable_push_join_below_union_all. 

When the GUC is enabled, the ORCA planner can created incorrect plans.

Resolution

Workaround

Disable the GUC:

# Change the setting in the config files:
gpconfig -c optimizer_enable_push_join_below_union_all -v off

# Reload the configuration
gpstop -u

gpconfig -s optimizer_enable_push_join_below_union_all -v off

Fix

As of July 2026, a fix is being developed and will be released in a future maintenance release.

Additional Information

Jira: TGP-27690