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Jack Ye
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OSS docs now own the full usage content for features that only run against an Enterprise deployment, since the client interface itself lives here; Enterprise docs keep only the parts specific to its own behavior. Sophon's overlay for these five pages is dropped since the OSS versions are now the complete reference. SQL Reference is restructured to match an object-type SQL manual (DDL by object, then DML, then DQL, then Expressions) instead of the old flat, loosely-ordered page list, absorbing the SQL client-connection guide and FTS-via-SQL examples into it.
66 lines
3.1 KiB
Plaintext
66 lines
3.1 KiB
Plaintext
---
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title: "Background jobs"
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sidebarTitle: "Background Jobs"
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description: "Jobs a deployment runs on its own — visible in SHOW JOBS, not started by a call you make."
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icon: gears
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keywords: ["background jobs", "job type", "wal", "spfresh", "prewarm", "archive"]
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---
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<Badge color="red">Enterprise</Badge>
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Every job documented elsewhere in these docs -- [Build & Repair](/indexing/reindexing),
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[Compaction](/maintenance/compaction), [Cleanup](/maintenance/cleanup),
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[Column Refresh](/feature-engineering/refresh-column) -- is one you cause,
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directly or by a schedule you set. This page is the rest: jobs the deployment
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runs to keep itself correct and fast, which you may see named in
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[`SHOW JOBS`](/sql/ddl/job#show) without having asked for any of them.
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There is no action to take on these beyond recognizing the name. None of them
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has a parameter you set or a call you make.
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## Write-ahead log maintenance {#wal}
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For a table with a [write-ahead log](/sql/ddl/table#properties) enabled, two jobs keep the
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log from growing without bound:
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| Job type | What it does |
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| --- | --- |
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| `sstable_compaction` | Folds a WAL bucket's SSTables into the base table by primary key. Distinct from `compact`, which merges base-table fragments -- the two are unrelated. |
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| `wal_index_catchup` | Extends a base-table index over the rows `sstable_compaction` just folded in, and records how far the index has caught up. Nothing else advances that record. |
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## Index maintenance {#index}
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| Job type | What it does |
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| --- | --- |
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| `index_remap` | Reassigns index entries after row ids shift underneath an index -- the kind of remap a delta compaction can require. |
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| `spfresh_merge` | Merges SPFresh-managed segments for indexes that use it. |
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## Cache warming {#cache}
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| Job type | What it does |
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| --- | --- |
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| `prewarm_page_cache` | Loads table data into a query node's page cache ahead of a request needing it. |
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| `prewarm_index_cache` | The same, for index structures. |
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| `startup_prewarm_idx` | Runs cache prewarming as part of a query node's own startup, rather than on a schedule. |
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## Registry housekeeping {#registry}
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| Job type | What it does |
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| --- | --- |
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| `job_registry_archive` | Sweeps terminal jobs out of the active registry and into archival storage, on a per-database schedule. |
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| `job_events_export` | Copies terminal jobs' event histories into a curated system table for metering. Registry-scoped, like the archive sweep. |
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These two are why an old job you completed weeks ago no longer shows in
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`SHOW JOBS` -- it was archived, not deleted; its events survive in the exported
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table.
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## Object teardown {#teardown}
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| Job type | What it does |
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| --- | --- |
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| `drop_object` | Deletes a dropped catalog object's content, then clears it from the database's cleanup backlog. Covers namespaces, views, and functions -- everything [`drop_table`](/management/table#drop) does not, since that one fences a directory with its own marker instead. |
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You trigger this indirectly, by dropping a [namespace](/management/namespace),
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[view](/sql/ddl/view#drop), or [function](/management/function#drop) -- the teardown
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itself runs as this job rather than inline with the call.
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