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MonetDB "forgets" columns after ALTER TABLE statements #6748

monetdb-team opened this issue Nov 30, 2020 · 0 comments

MonetDB "forgets" columns after ALTER TABLE statements #6748

monetdb-team opened this issue Nov 30, 2020 · 0 comments


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@monetdb-team monetdb-team commented Nov 30, 2020

Date: 2019-08-14 10:18:57 +0200
From: @drstmane
To: SQL devs <>
Version: 11.33.3 (Apr2019)
CC: @njnes

Last updated: 2019-09-02 16:05:26 +0200

Comment 27215

Date: 2019-08-14 10:18:57 +0200
From: @drstmane

I have a situation where after bulk-loading CSV data (8k rows in a 696 column table) and then adding/removing columns, the removed columns are only usable while the server is still running, but "disappear" after a server restart.
Also, before the restart, the added columns seem to be missing in the SQL catalogue (sys.columns) and (hence?) in the ANALYZE-generates sys.statistics .

For now, I only have a showcase with non-public data that I cannot share in this bug report. I'll try to find time to reproduce it with public/synthetic data.

Till then, maybe this already rings a bell with someone?

I happens with both Apr2019 feature release and Apr2019-SP1 bugfix release candidate/preview.

Comment 27217

Date: 2019-08-14 11:41:44 +0200
From: @drstmane

Created attachment 624
test for bug

Attached file: Bug-6748.tar (application/x-tar, 665600 bytes)
Description: test for bug

Comment 27218

Date: 2019-08-14 11:47:13 +0200
From: @drstmane

Test added as attachment to this bug report.

if the added column is also declared as foreign key,
restarting the server fails with

2019-08-14 11:45:06 ERR DBname[8848]: mserver5: /export/scratch1/home/manegold/_/Monet/release/source/MonetDB/sql/storage/store.c:406: load_idxcolumn: Assertion `kc->c' failed.

(or segfault in case not debug build)

Comment 27219

Date: 2019-08-14 12:23:10 +0200
From: @njnes

The server failed to create the needed binary tables. Fix is coming soon.

Comment 27220

Date: 2019-08-14 12:28:49 +0200
From: MonetDB Mercurial Repository <>

Changeset 164eee74d3cf made by Niels Nes in the MonetDB repo, refers to this bug.

For complete details, see https//devmonetdborg/hg/MonetDB?cmd=changeset;node=164eee74d3cf

Changeset description:

fixes for bug #6748
- incase of new tables the delta's bid isn't used yet, so also alters should not use it
- added error messages when delta structure creation fails

Comment 27229

Date: 2019-08-18 14:44:10 +0200
From: @drstmane

Many thanks for the instant fix!
Appears to work perfectly, now.

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