Module preprocessor 

SQL dialect-specific preprocessing.

This module transforms SQL statements to remove or normalize constructs that are not supported by the sqlparser crate, while preserving the semantic meaning for analysis.

Supported Dialects

• ClickHouse: Handles CODEC, TTL, SETTINGS clauses

Architecture

The preprocessor operates in two phases:

1. Extraction: Captures dialect-specific metadata (codecs, TTL rules)
2. Transformation: Removes unsupported syntax for clean parsing

Example

use sql_query_analyzer::{preprocessor::Preprocessor, query::SqlDialect};

let sql = "CREATE TABLE logs (data String CODEC(ZSTD)) ENGINE = MergeTree ORDER BY id";
let result = Preprocessor::new(SqlDialect::ClickHouse).process(sql);

assert!(!result.sql.contains("CODEC"));
assert!(result.metadata.codecs.contains_key("data"));

Modules

clickhouse

ClickHouse-specific SQL preprocessing.

Structs

Preprocessor

Preprocessor for dialect-specific SQL transformations.

PreprocessorMetadata

Metadata extracted during preprocessing.

PreprocessorResult

Result of SQL preprocessing.