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Michael Paquier cd4868a570 pageinspect: Fix handling of all-zero pages ... Getting from get_raw_page() an all-zero page is considered as a valid case by the buffer manager and it can happen for example when finding a corrupted page with zero_damaged_pages enabled (using zero_damaged_pages to look at corrupted pages happens), or after a crash when a relation file is extended before any WAL for its new data is generated (before a vacuum or autovacuum job comes in to do some cleanup). However, all the functions of pageinspect, as of the index AMs (except hash that has its own idea of new pages), heap, the FSM or the page header have never worked with all-zero pages, causing various crashes when going through the page internals. This commit changes all the pageinspect functions to be compliant with all-zero pages, where the choice is made to return NULL or no rows for SRFs when finding a new page. get_raw_page() still works the same way, returning a batch of zeros in the bytea of the page retrieved. A hard error could be used but NULL, while more invasive, is useful when scanning relation files in full to get a batch of results for a single relation in one query. Tests are added for all the code paths impacted. Reported-by: Daria Lepikhova Author: Michael Paquier Discussion: https://postgr.es/m/561e187b-3549-c8d5-03f5-525c14e65bd0@postgrespro.ru Backpatch-through: 10		3 years ago
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brin.out	pageinspect: Fix handling of all-zero pages	3 years ago
btree.out	pageinspect: Fix handling of all-zero pages	3 years ago
checksum.out	Add an explicit test to catch changes in checksumming calculations.	6 years ago
checksum_1.out	Add an explicit test to catch changes in checksumming calculations.	6 years ago
gin.out	pageinspect: Fix handling of all-zero pages	3 years ago
gist.out	pageinspect: Fix handling of all-zero pages	3 years ago
hash.out	pageinspect: Fix handling of all-zero pages	3 years ago
oldextversions.out	pageinspect: Improve page_header() for pages of 32kB	4 years ago
page.out	pageinspect: Fix handling of all-zero pages	3 years ago