cdb: fix SEGFAULT for gpdb builded with cassert#381
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ADB 6.21.1_arenadata36 release
Partition exchanging with different distribution policy may produce `SEGFAULT` at gpdb builded with `--enable-cassert`. If table, that are exhanging, has deleted column and has difference in distribution policy with parent table (ex. parent was created with default policy and new table created with `GpPolicy` `distributed randomly`, or distribution column was dropped at new table) then operation: `alter table parent_tbl exhange partition for ... with exchange_tbl` may produce `SEGFAULT` at function `is_exchangeble`. In case described above, `Assert(newpol->attrs[i] > 0)`, checks that new `GpPolicy` (of new table) has distribution keys, but it doesn't have them (`attrs` is `NULL` and `nattrs`=0), so a NULL pointer dereference occurs. This assertion, seems, should be deleted, because next access to `attrs` is at function `GpPolicyEqual(adjpol, newpol)` (in the code below), but before accessing to `attrs` function validates equality of the GpPolicie's `nattrs`, if them not equal this function returns false and `attrs` won't be accessed.
RekGRpth
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Aug 25, 2022
Stolb27
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Aug 29, 2022
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Thank you, @HustonMmmavr. Thank you, @RekGRpth, for review.
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Partition exchanging with different distribution policy may produce
SEGFAULTat gpdb builded with--enable-cassert.If table, that are exhanging, has deleted column and has difference in
distribution policy with parent table (ex. parent was created with
default policy and new table created with
GpPolicydistributed randomly, or distribution column was dropped at new table)then operation:
alter table parent_tbl exhange partition for ... with exchange_tblmay produce
SEGFAULTat functionis_exchangeble.In case described above,
Assert(newpol->attrs[i] > 0), checks thatnew
GpPolicy(of new table) has distribution keys, but it doesn'thave them (
attrsisNULLandnattrs=0), so a NULL pointerdereference occurs.
This assertion, seems, should be deleted, because next access to
attrsis at functionGpPolicyEqual(adjpol, newpol)(in the codebelow), but before accessing to
attrsfunction validates equality ofthe GpPolicie's
nattrs, if them not equal this function returns falseand
attrswon't be accessed.Here are some reminders before you submit the pull request
make installcheck