"cache lookup failed for..." error in Tanzu Greenplum

Products

• VMware Tanzu Greenplum

Issue/Introduction

Drop commands might fail with cache lookup failure errors such as:

ERROR: cache lookup failed for relation
ERROR: cache lookup failed for namespace

Environment

Product Version: 5.28

Resolution

Cache lookup failures are usually related to index problems. The first step is always to rebuild the index to rule out index corruption.

Example pg_class error:

# drop table my_table;
ERROR: cache lookup failed for relation 1012608 (utility.c:212) (seg2 sdw1:40002 pid=10204) (cdbdisp.c:1528)

To resolve this error, reindex pg_class:

# REINDEX TABLE pg_class ;
REINDEX

Example pg_depend error:

# DROP ROLE my_role;
ERROR: cache lookup failed for namespace 2719529 (dependency.c:2271)

To resolve this error, reindex pg_depend:

# reindex table pg_depend ;
REINDEX

If you are not sure what catalog table you should reindex, you can reindex all system tables using this command:

gpadmin=# reindex system <db name>;
NOTICE:  table "gp_configuration_history" has no indexes
NOTICE:  table "gp_id" has no indexes
NOTICE:  table "gp_version_at_initdb" has no indexes
REINDEX

Note: Reindexing catalog takes locks and it might be worth to perform it during maintenance in restricted mode if you have a buys cluster with many queries. 

If the problem still exist after performing a system reindex, it might be a data corruption in system catalog. Continue with gpcheckcat to check the catalog integrity. For more information about gpcheckcat, refer to: How to run gpcheckcat on a Tanzu Greenplum Database