@keboola/sql-splitter

Splits a SQL script into the fragments the SQL editor runs and stores.

import { splitStatements } from '@keboola/sql-splitter';

splitStatements("SELECT 'a;b';\nSELECT 2;", 'snowflake');
// ["SELECT 'a;b';", "\nSELECT 2;"]

Why it is not a regex

Statement boundaries depend on which constructs a dialect treats as opaque. A regex that encodes them needs nested quantifiers over an alternation, which backtracks catastrophically as soon as a quote or a comment is left open — and the editor re-splits a document that is still being typed.

Boundaries here come from the CodeMirror SQL grammar (@codemirror/lang-sql), the same tokenizer the editor already runs. Quotes, dollar-quotes, comment syntax and identifier quoting follow the dialect definition instead of a hand-written scan, so '', "", backslash escapes and nested block comments come for free.

Guarantees

• Total. Fragments always re-join to the input, including for unterminated literals and comments. A script the splitter cannot make sense of is still a script the user can run, and the backend gives a better syntax error than we can. A fragment is usually one statement, but a script can also yield a bare ; or a trailing comment.
• Linear. One pass over the input and one over its tokens. No input makes it backtrack, and the work per byte does not climb with the size of the script — there is a test for that shape, not for a wall-clock threshold.

Dialects

| | Snowflake | BigQuery | | --------- | ----------------- | ----------------- | | "…" | quoted identifier | string | | `…` | not special | quoted identifier | | $$…$$ | string | not special | | # | not a comment | line comment | | // | line comment | not a comment |

Tests

splitStatements.test.ts is the readable spec. behaviour.test.ts is the safety net: a characterisation matrix of 1,440 cases per dialect — every lexical construct alone, next to every separator, and paired with every other construct — snapshotted whole, so a change anywhere shows up as a reviewable diff rather than a single failing assertion.