Fix on-demand SLRU download on standby starting at WAL segment boundary #8031
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If a standby is started right after switching to a new WAL segment, the request in the SLRU download request would point to the beginning of the segment (e.g. 0/5000000), while the not-modified-since LSN would point to just after the page header (e.g. 0/5000028). It's effectively the same position, as there cannot be any WAL records in between, but the pageserver rightly errors out on any request where the request LSN < not-modified since LSN. To fix, round down the not-modified since LSN to the beginning of the page like the request LSN. Fixes issue #8030
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If a standby is started right after switching to a new WAL segment, the request in the SLRU download request would point to the beginning of the segment (e.g. 0/5000000), while the not-modified-since LSN would point to just after the page header (e.g. 0/5000028). It's effectively the same position, as there cannot be any WAL records in between, but the pageserver rightly errors out on any request where the request LSN < not-modified since LSN. To fix, round down the not-modified since LSN to the beginning of the page like the request LSN. Fixes issue #8030
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3216 tests run: 3074 passed, 0 failed, 142 skipped (full report)Flaky tests (2)Postgres 16
Postgres 15
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2099e9d at 2024-06-12T14:17:18.762Z :recycle: |
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…ry (#8031) If a standby is started right after switching to a new WAL segment, the request in the SLRU download request would point to the beginning of the segment (e.g. 0/5000000), while the not-modified-since LSN would point to just after the page header (e.g. 0/5000028). It's effectively the same position, as there cannot be any WAL records in between, but the pageserver rightly errors out on any request where the request LSN < not-modified since LSN. To fix, round down the not-modified since LSN to the beginning of the page like the request LSN. Fixes issue #8030
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If a standby is started right after switching to a new WAL segment, the request in the SLRU download request would point to the beginning of the segment (e.g. 0/5000000), while the not-modified-since LSN would point to just after the page header (e.g. 0/5000028). It's effectively the same position, as there cannot be any WAL records in between, but the pageserver rightly errors out on any request where the request LSN < not-modified since LSN.
To fix, round down the not-modified since LSN to the beginning of the page like the request LSN.
Fixes issue #8030