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"Header checksum does not match" an error for Append-Only tables

Note: This article is only applicable when a user upgrades to a higher version of Pivotal Greenplum and then downgrades to below to 4.3.4.0, when checksum was introduced.

Environment

Product Version
Pivotal Greenplum (GPDB) 4.3.x, 4.2.x
OS RHEL 6.x
Others  

Symptom

Append only tables are inaccessible by the users and result with the following error.

Error Message:

Header checksum does not match. Expected 0xAA2A471 and found 0x7421918B (cdbappendonlystorageread.c:849) (seg0 slice1 sdw1:40000 pid=6567) (cdbdisp.c:1525)
DETAIL:
Append-Only storage Small Content header: smallcontent_bytes_0_3 0x19011C0F, smallcontent_bytes_4_7 0xCAC01DBA, headerKind = 1, executorBlockKind = 1, rowCount = 71, usingChecksums = true, header checksum 0xAA2A471, block checksum 0x28FAC5BD, dataLength 32342, compressedLength 7610, overallBlockLen 7632

Cause 

Checksum storage is introduced in GPDB 4.3.4.0. After upgrading to 4.3.4.0 or higher, if the cluster is downgraded to a lower version, the checksum feature does not work and is likely to throw the above error.

Please refer to the documentation for more information: Greenplum Database 4.3.4 Release Notes.

Troubleshooting Steps

  1. Verify with the customer if they have inserted data into the Append-Only (AO) tables after downgrading.
  2. Turn checksum off and run a select on the table to check if it works:
set gp_appendonly_verify_block_checksums=false;
  1. Check /usr/local to confirm if there are any newer versions of Greenplum (higher than 4.3.4.0) installed.

Resolution

Check if the cluster has been recently downgraded from 4.3.4.0 or to a lower version. If yes, then upgrade the cluster back to GPDB 4.3.4.0 or higher. 

Additional Reference

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