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Jack Ye
5b5ed930ac
Every group now answers exactly one question. Get started and Concepts cover what the system is; the verb groups cover doing something with it; Operate, Secure and Deploy cover running it; SQL reference is lookup. Maintenance becomes Operate, Governance becomes Secure, and the rest take verbs to match. Three new pages in Concepts and Get started: Guarantees states what a write promises when it returns, which version a reader sees, what survives a failure, and -- the half usually missing -- what is not guaranteed: no multi-table transactions, no read-your-writes across processes without an interval, unenforced primary keys that do not enforce, no background compaction. Limits collects bounds that were stated in passing across a dozen pages, with the numbers verified against the code rather than inferred: name lengths, job event caps, SHOW ERRORS bounds, the sampling range that is refused rather than clamped. Architecture illustrates embedded against distributed as the one deployment decision, and is written to cover both rather than only Enterprise. Indexing splits by question. Choosing an index is a Query decision and moves there; building, repairing and GPU-building it stay in Operate. SQL becomes a top-level reference of fifteen pages instead of a sub-group of Query. Auditing sophon-sql turned up a large undocumented surface: ALTER TABLE ADD COLUMN in its plain, computed and function forms with FILTER, IGNORE NULLS and OVER modifiers; SET UNENFORCED PRIMARY KEY; SET and UNSET WAL with sharding; CREATE FUNCTION with its dependency options; REFRESH COLUMN and REFRESH MATERIALIZED VIEW; and the SHOW family. None of it was written down.
82 lines
2.7 KiB
Plaintext
82 lines
2.7 KiB
Plaintext
---
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title: "Operators and literals"
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sidebarTitle: "Operators"
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description: "Comparison, logical and arithmetic operators, literals, and precedence."
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icon: plus-minus
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keywords: ["operators", "literals", "precedence", "null", "cast", "interval"]
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---
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<Badge color="red">Enterprise</Badge> [SQL runs on a deployment.](/sql)
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The operator set is DataFusion's. This page covers what is worth knowing when
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the operands are Lance columns.
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## Comparison {#comparison}
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| --- | --- |
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| `=` `!=` `<>` `<` `<=` `>` `>=` | ordinary comparison |
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| `IS NULL` / `IS NOT NULL` | null test — `= NULL` is never true |
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| `IS DISTINCT FROM` | comparison that treats null as a value |
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| `BETWEEN a AND b` | inclusive range |
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| `IN (...)` | set membership |
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| `LIKE` / `ILIKE` | pattern match, `%` and `_` |
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| `~` `~*` `!~` | regular expression match |
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<Note>
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For keyword matching on a text column, [`contains_tokens`](/sql/functions#contains-tokens)
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is index-accelerated where `LIKE` is not. Reach for `LIKE` only when you need
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its wildcard semantics.
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</Note>
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## Logical {#logical}
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`AND`, `OR`, `NOT`. Three-valued: a comparison against null is **unknown**, and
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`NOT unknown` is still unknown. A `WHERE` clause keeps only rows where the
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predicate is true, so unknown behaves like false there — but not inside `NOT
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IN`, which is the usual place this bites. See
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[Subqueries](/sql/subqueries#in-exists).
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## Arithmetic {#arithmetic}
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`+` `-` `*` `/` `%`, with the usual precedence. String concatenation is `||`.
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<Warning>
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Arithmetic over a vector column is **list** arithmetic, not scalar arithmetic —
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a vector is a `FixedSizeList<Float32>`. When the operation you want is a
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similarity comparison, use [vector search](/search/vector-search); there is no
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SQL form for it.
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</Warning>
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## Literals {#literals}
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| --- | --- |
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| String | `'text'` — doubled quote to escape: `'it''s'` |
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| Number | `42`, `3.14` |
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| Boolean | `TRUE`, `FALSE` |
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| Null | `NULL` |
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| Date / timestamp | `DATE '2026-01-01'`, `TIMESTAMP '2026-01-01 12:00:00'` |
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| Interval | `INTERVAL '7 days'` |
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| Array | `[1, 2, 3]` |
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Identifiers are quoted with double quotes when they need to be — a reserved word
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or a name with mixed case: `SELECT "order" FROM "MyTable"`.
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## Casting {#casting}
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```sql
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SELECT CAST(identifier AS VARCHAR), identifier::VARCHAR FROM documents
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```
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Both forms work. `TRY_CAST` returns null instead of erroring on a value that
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will not convert, which is the one to use over a column you do not control.
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## Precedence {#precedence}
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Highest to lowest: `::` → unary `-` → `* / %` → `+ -` → `||` → comparison →
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`IS` → `NOT` → `AND` → `OR`.
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Parenthesize anything mixing `AND` and `OR`. `a OR b AND c` is `a OR (b AND c)`,
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which is rarely what was meant.
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