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Brendan Clement
305dffe27b
The earlier change dropped every statement that a materialized view's
source needs stable row ids, because main no longer requires them. That
holds for the local SDK only. Sophon main creates a view through SQL by
default with the creation checks of its pinned lancedb (00f5dd6f), which
predates #4373 and still rejects a source without stable row ids.
The refresh and management pages now say a local view needs no special
source and a deployment may still require stable row ids, and the
architecture, limits, table and database pages note that requirement.
The summaries say a refresh brings a view up to date instead of saying
it recomputes it, since a deployment may reconcile changes rather than
rebuild.
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** -- the one schema
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decision here that is genuinely irreversible. A deployment may require them on a
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[materialized view](/management/materialized-view) source; a local view does
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not.
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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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