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Structural query analysis

Source: R/analysis.R
sql_analyze.Rd

Extracts compact facts about a query: its shape, output projections, referenced relations, CTEs, set operations and star-projections.

Usage

sql_analyze(sql, dialect = "generic", schema = NULL)

Arguments

sql

A single character string with one or more SQL statements (separated by ;).

dialect

Dialect used for parsing.

schema

Optional schema specification (see as_polyglot_schema()); improves resolution of unqualified or ambiguous columns.

Value

A polyglot_analysis object — a list with (among others):

  • shape — query shape (e.g. "select", "setOperation");

  • projections — list of per-output-column facts (name, transform kind, upstream column references, type hints when a schema is given);

  • relations — list of referenced relations with kind and alias;

  • ctes, cteFacts — CTE names and per-CTE facts;

  • setOperations, starProjections — when present.

Examples

a <- sql_analyze("WITH x AS (SELECT id FROM t) SELECT x.id, 2 AS two FROM x")
a$shape
#> [1] "select"
vapply(a$projections, function(p) p$name, character(1))
#> [1] "id"  "two"