Fix #7664: DROP TABLE executed for a table with big records may lead to "wrong page type" or "end of file" error #7666
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…lead to "wrong page type" or "end of file" error The reason is that rhd_large flag can be set while rhd_incomplete flag is not set. It happens when a record which has 2 or more fragments is updated to a smaller record which fits on one page.
src/jrd/dpm.epp
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| CCH_RELEASE_TAIL(tdbb, &window); | ||
| PAG_release_page(tdbb, window.win_page, ZERO_PAGE_NUMBER); | ||
| if (dpage->dpg_header.pag_flags & dpg_orphan) |
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Could you explain this condition ?
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If a database was created by the server which doesn't have the fix, it's possible to get a secondary data page here. But the code below works only for orphan data pages. It's just a protection from incorrect usage of rpb_large/rhd_large flag.
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The code used to release data pages allocated for fragments of big records when relation is dropped.
Fragments are allocated on own separate data pages and is not marked as orphan.
How this new code is going to release fragment's pages ?
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Sorry, fragment's page is marked as orphan, I missed it.
But it could be better (safer) to check also dpg_full flag and number of records on page, same as in analyze_fragments() at dba.epp
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Fragments are allocated on own separate data pages and is not marked as orphan.
How this new code is going to release fragment's pages ?
If a data page is not an orphan then it's included in a pointer page. Such pages will be released in DPM_delete_relation_pages function (note that it checks rhd_large flag for secondary data pages as well). It's not the task of delete_tail function.
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But it could be better (safer) to check also
dpg_fullflag and number of records on page, same as inanalyze_fragments()at dba.epp
I agree. But I just looked at analyze_fragments() and the condition there is a bit confusing for me. If a data page has dpg_full and dpg_count = 1 but doesn't have dpg_orphan, the condition is still true, right?
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Yes, analyze_fragments() is not as accurate (or paranoid) as it might be ;)
But you get the idea - lets check for all 3 conditions to be absolutely sure.
Fix #7664: DROP TABLE executed for a table with big records may lead to "wrong page type" or "end of file" error
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