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Jack Ye
c220e63828
SQL now leads with why you'd reach for it beyond analytics: it's served over Flight SQL, so it's the way in for any language without a native LanceDB SDK, and broadly every public SDK method has a corresponding SQL statement. Closes by pointing at the SQL Reference as the spec that defines the precise behavior behind both the SQL surface and the SDK operations it mirrors. Moving both into Getting Started (before Agentic Skills) means a reader knows what the API surface even is before being told how to hand it to an agent.
104 lines
3.6 KiB
Plaintext
104 lines
3.6 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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This page covers bounds that are the same for everyone. Deployment-specific
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quotas -- storage, throughput, concurrency -- come from your 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.
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## Jobs {#jobs}
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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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Stable row ids **cannot be enabled after a table exists**. A table created
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without them cannot become a
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[materialized view](/management/materialized-view) source without being
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recreated -- the one schema decision here that is genuinely irreversible.
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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` | parsed, not yet implemented |
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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 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 | no SQL form; use a query builder |
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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 two 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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