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https://issues.apache.org/jira/browse/OAK-3872?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15095786#comment-15095786
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Thomas Mueller edited comment on OAK-3872 at 1/13/16 7:51 AM:
--------------------------------------------------------------
The patch looks good to me. I think the bug in the original code was that the
comparison was wrong:
{noformat}
// correct:
// delete only if the last modified is older than x
metaStatement.append(" and LASTMOD <= ?");
// wrong:
// delete only if there is NO entry where the last modified of the meta is
older than x
dataStatement.append(" and not exists(select * from " + this.tnMeta + " m where
ID = m.ID and m.LASTMOD <= ?)");
// correct would also be:
// delete if there is NO entry where the last modified of the meta is YOUNGER
than x
dataStatement.append(" and not exists(select * from " + this.tnMeta + " m where
ID = m.ID and m.LASTMOD > ?)");
{noformat}
But the patch is also fine. The logic is a bit different: delete if there is no
meta record. This is correct if the meta record is removed before the data
record. Please note it would not be correct if the data record is removed
before the meta record. But that's not the case:
{noformat}
count += prepMeta.executeUpdate();
prepData.execute();
{noformat}
I guess it would be good to add comments in the code, to avoid adding bugs
later on.
was (Author: tmueller):
The patch looks good to me. I think the bug in the original code was that the
comparison was wrong:
{noformat}
// correct:
// delete only if the last modified is older than x
metaStatement.append(" and LASTMOD <= ?");
// wrong:
// delete only if there is NO entry where the last modified of the meta is
older than x
dataStatement.append(" and not exists(select * from " + this.tnMeta + " m where
ID = m.ID and m.LASTMOD <= ?)");
// correct would also be:
// delete if there is NO entry where the last modified of the meta is YOUNGER
than x
dataStatement.append(" and not exists(select * from " + this.tnMeta + " m where
ID = m.ID and m.LASTMOD > ?)");
{noformat}
But the patch is also fine. The logic is a bit different: delete if there is no
meta record. This is correct if the meta record is removed before the data
record. Please note it would not be correct if the data record is removed
before the meta record, which is the case:
{noformat}
count += prepMeta.executeUpdate();
prepData.execute();
{noformat}
I guess it would be good to add comments in the code, to avoid adding bugs
later on.
> [RDB] Updated blob still deleted even if deletion interval lower
> ----------------------------------------------------------------
>
> Key: OAK-3872
> URL: https://issues.apache.org/jira/browse/OAK-3872
> Project: Jackrabbit Oak
> Issue Type: Bug
> Components: blob, rdbmk
> Reporter: Amit Jain
> Assignee: Julian Reschke
> Attachments: OAK_3872.patch
>
>
> If an existing blob is uploaded again, the timestamp of the existing entry is
> updated in the meta table. Subsequently if a call to delete
> (RDBBlobStore#countDeleteBlobs) is made with {{maxLastModifiedTime}}
> parameter of less than the updated time above, the entry in the meta table is
> not touched but the data table entry is wiped out.
> Refer
> https://github.com/apache/jackrabbit-oak/blob/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/document/rdb/RDBBlobStore.java#L510
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