Queries failing for specific users with "Unexpected internal error (cdbgang.c:1673)"

Products

• VMware Tanzu Greenplum

Issue/Introduction

Certain users are unable to run queries on user tables:

database1=> select * from table1 limit 1;                                                                                         
ERROR:  Unexpected internal error (cdbgang.c:1673)

In the master logs, you see the following message repeatedly:

2019-09-24 17:50:41.115430 CST,"user1","database1",p8118,th-229218528,"10.4.1.37","52102",2019-09-24 17:17:18 CST,105154501,
con8075305,,seg-1,,dx11691594,x105154501,sx1,"LOG","XX000","Internal error: AddOption search_path failed (cdbgang.c:443)",,,,,,"set optimizer=on"
,0,,"cdbgang.c",443,

Then the following stack trace:

2019-09-24 17:33:59.468775 CST,"user1","database1",p26956,th-229218528,"[local]",,2019-09-24 17:33:41 CST,105153096,con8074818,,se
g-1,,dx11690826,x105153096,sx1,"ERROR","XX000","Unexpected internal error (cdbgang.c:1673)",,,,,,"set gp_log_gang ='debug';",0,,"cdbgang.c"
,1673,"Stack trace:
1    0xb07a42 postgres <symbol not found> (elog.c:502)
2    0xb0beb2 postgres elog_internalerror (elog.c:279)
3    0xc31cc1 postgres allocateWriterGang (cdbgang.c:1640)
4    0xbe8b55 postgres CdbSetGucOnAllGangs (cdbdisp.c:4350)
5    0xb39927 postgres SetPGVariable (guc.c:10748)
6    0x9a8a84 postgres ProcessUtility (utility.c:1466)
7    0x9a535b postgres PortalRun (pquery.c:1506)
8    0x99c28c postgres <symbol not found> (postgres.c:1824)
9    0x9a0689 postgres PostgresMain (postgres.c:4779)
10   0x8fabe9 postgres <symbol not found> (postmaster.c:6672)
11   0x8fd690 postgres PostmasterMain (postmaster.c:7603)
12   0x7fd50f postgres main (main.c:206)
13   0x3b21c1ed1d libc.so.6 __libc_start_main + 0xfd
14   0x4bee79 postgres <symbol not found> + 0x4bee79

Environment

Product Version: 4.3

Resolution

This has been identified as a product limitation in the Greenplum code.

There is a function that will error out when a GUC is set to a value length higher than 1023 characters and the value will not be dispatched to segments.

This limitation is not in Greenplum Database (GPDB) 5, so it will accept any length GUC.

This fix will be available in the next GPDB 4.x version. The issue number is 30151 and will be available in the release notes.