Querying a column that has unprocessed modifications involves copying the bat so that the modifications can be applied to the copy.  If the column is simultaneously further modified (appended to) by another query, it can happen that the string heap is modified (both extended and its hash table changed) after the size of the heap is recorded and before the data is actually copied.  This can result in a copy with a hash table that has entries that point beyond the end of the (copied) string heap, potentially resulting in a crash.



Crash when simultaneously querying and updating a string column.
This is a GitHub Issue
repo:MonetDB
owner:MonetDB
Title : Crash when simultaneously querying and updating a string column.
Issue date:

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Querying a column that has unprocessed modifications involves copying the bat so that the modifications can be applied to the copy.  If the column is simultaneously further modified (appended to) by another query, it can happen that the string heap is modified (both extended and its hash table changed) after the size of the heap is recorded and before the data is actually copied.  This can result in a copy with a hash table that has entries that point beyond the end of the (copied) string heap, potentially resulting in a crash.



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