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Holger Rehn updated DERBY-7109: ------------------------------- Attachment: DerbyTest.java > SYSCS_UTIL.SYSCS_INPLACE_COMPRESS_TABLE doesn't work as expected > ---------------------------------------------------------------- > > Key: DERBY-7109 > URL: https://issues.apache.org/jira/browse/DERBY-7109 > Project: Derby > Issue Type: Bug > Components: Store > Affects Versions: 10.14.2.0, 10.15.2.0 > Reporter: Holger Rehn > Priority: Major > Attachments: DerbyTest.java > > > The SYSCS_UTIL.SYSCS_INPLACE_COMPRESS_TABLE procedure seems to be unable to > reclaim any disk space under almost all circumstances. I have a number of > existing DBs that I tried to reorganize to reclaim disk space using the > mentioned procedure. Because that didn't even free the smallest amount of > space, I started a number of tests and it looks like inplace compression > simply doesn't work, at all. > Example: > One of the DBs uses ~37 GB of disk space and the exact same amount after > running SYSCS_UTIL.SYSCS_INPLACE_COMPRESS_TABLE. After using > SYSCS_UTIL.SYSCS_COMPRESS_TABLE to reorganize the DB it only uses 20,4 GB of > disk space. This might be correct, if I correctly understand how inplace > compression should work - but is not really what I expected. But even after I > completely deleted a number of tables and removed more than 90% of the rows > from all other tables of the original DB, > SYSCS_UTIL.SYSCS_INPLACE_COMPRESS_TABLE was unable to reclaim any disk space. > In contrast, SYSCS_UTIL.SYSCS_COMPRESS_TABLE now reduced the DB size to ~ > 130MB. To carry this to the extreme, I completely removed any data from all > tables. As expected, procedure SYSCS_UTIL.SYSCS_COMPRESS_TABLE now results in > an empty DB only taking up ~4 MB of disk space, while > SYSCS_UTIL.SYSCS_INPLACE_COMPRESS_TABLE was still unable to reclaim a > relevant amount of disk space (only ~ 4,6GB), leaving a completely empty DB > still occupying more than 32 GB of disk space. > In all calls to SYSCS_UTIL.SYSCS_INPLACE_COMPRESS_TABLE I set PURGE_ROWS, > DEFRAGMENT_ROWS, and TRUNCATE_END to 1. -- This message was sent by Atlassian Jira (v8.3.4#803005)