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Brendan Clement
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Creating, writing, updating, merging and deleting rows, managing tables, branches and read consistency work in the embedded library and on a deployment, and those pages now say so. The SQL forms they mention need a deployment. Where the offerings differ, the section says how: a deployment reuses an existing table without comparing schemas, a merge insert can be refused past a configured number of unindexed rows, space is reclaimed by optimize() locally and by the deployment's compaction and configured cleanup otherwise, renaming depends on the catalog, a deployment clones shallowly only, drops all tables only locally, keeps freshness state per table handle and defaults freshness to its own setting, and refuses to delete a branch main depends on. table_exists works only on a namespace connection. Guarantees and limits span both offerings, so they carry section notes rather than a label: reads, retention, index freshness and compaction differ on a deployment, and the name and job limits are a deployment's.
113 lines
4.3 KiB
Plaintext
113 lines
4.3 KiB
Plaintext
---
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title: "Limits"
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sidebarTitle: "Limits"
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description: "The bounds you can actually hit, in one place."
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icon: ruler
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keywords: ["limits", "maximum", "quota", "constraints", "bounds"]
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---
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Limits worth designing around, collected so you do not have to find them by
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hitting them. Each one is enforced -- where a value is refused rather than
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clamped, that is stated, because the two fail very differently.
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Some of these bounds apply only on a deployment, as their sections say. Quotas
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that a deployment sets -- storage, throughput, concurrency -- come from your
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deployment.
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## Names {#names}
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| Object | Maximum | |
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| --- | --- | --- |
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| Database | 64 characters | |
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| Namespace | 64 characters | |
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| Table | 128 characters | |
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| Branch | 64 characters | |
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A name must not be empty, and must not contain `$` or `:` -- both are reserved
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as path delimiters, so a name holding one could not be addressed unambiguously.
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Length is counted in characters, not bytes. These lengths are a deployment's
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limits; the embedded library does not limit name length.
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## Jobs {#jobs}
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<Badge color="red">Enterprise</Badge> These bounds belong to a deployment's job
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service. Jobs on a local database run in-process and keep no event history.
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| | |
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| --- | --- |
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| `job.events()` default | 1,000 rows |
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| `job.events()` maximum | 10,000 rows |
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| `SHOW ERRORS ... LIMIT` | between 1 and 100,000 |
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| Failed jobs scanned by one `SHOW ERRORS` | 32 |
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<Warning>
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`job.events()` **truncates silently**. A job that emits an event per fragment
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will lose its tail unless you pass `limit` explicitly. This is the limit on this
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page most likely to mislead you, because nothing in the result says it was cut.
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</Warning>
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`SHOW ERRORS` without `FOR JOB` scans the most recent failed jobs and stops at
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32 of them. Narrow with `FOR JOB` when you need a specific one rather than a
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survey.
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See [Jobs](/basics/jobs).
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## Schema and types {#schema}
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| --- | --- |
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| `map` with `keys_sorted = true` | rejected |
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| `IVF_RQ` vector dimensions | must be divisible by 8 |
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| FTS `max_token_length` | 40 by default; longer tokens are dropped |
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Through the SDK, a table gets **stable row ids** only at creation, from the
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`new_table_enable_stable_row_ids` storage option on a local path or an object
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store; no SDK call adds them later, so decide early. A local
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[materialized view](/feature-engineering/materialized-views#stable-row-ids) does
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not need them. On a deployment, whether a view's source needs them and how a
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table gets them depend on the deployment; see
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[Against a deployment](/feature-engineering/materialized-views#availability).
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See [Data types](/sql/data-types).
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## SQL {#sql}
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<Badge color="red">Enterprise</Badge>
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| --- | --- |
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| `TABLESAMPLE` percentage | 0 to 100, **refused** outside -- not clamped |
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| `TABLESAMPLE (n ROWS)` | whole numbers only |
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| `TABLESAMPLE BUCKET` | not supported |
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| `TABLESAMPLE` on a WAL-backed table | not supported |
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| `CREATE INDEX` | one column, server-chosen name |
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| `REFRESH MATERIALIZED VIEW ... CASCADE` | depends on the deployment's version; see [REFRESH](/sql/dml/refresh#refresh-materialized-view) |
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A sampling percentage over 100 is an error rather than a full scan, because a
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query asking for 150 percent has a mistake in it and reading it as 100 would
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hide the mistake. See [Sampling](/sql/dql/sampling).
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## What is unavailable where {#availability}
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Not quotas, but the same class of surprise -- things that exist in one place and
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not another.
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| --- | --- |
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| SQL on a local database | unavailable; `execute_query` raises |
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| SQL on a deployment | needs its Flight SQL endpoint enabled and reachable |
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| SQL methods in the TypeScript SDK | none; use a Flight SQL client |
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| Function methods in the TypeScript SDK | none; use Python or SQL |
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| Vector search in SQL | [depends on the deployment](/basics/sql#no-vector-sql); the query builder always has it |
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| Geospatial `st_*` functions | behind a build feature LanceDB does not ship |
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| `tableExists` / `namespaceExists` in TypeScript | not present |
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| Server-side jobs on a local database | run in-process; `events()` raises |
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See [SQL](/basics/sql) for why the first three hold.
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## Nothing here is a quota {#not-quotas}
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None of the above is a billing or capacity limit. Rows per table, table count,
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storage, and request rate are bounded by your deployment rather than by the
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format -- ask your deployment, not this page.
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