Column-Level Lineage: An Adventure in SQL Parsing

Column-level lineage is a crucial aspect in the data space, as it traces data not just from table to table but also from column to column. This provides valuable insights into how data moves and can enable finer-tuned root cause analysis and more robust downstream issue prevention. Metaplane's approach to column-level lineage involves building a complete SQL parser using the ANTLR library, which converts raw SQL statements into an abstract syntax tree (AST). The AST is then used to walk through the SQL statement and pull out relevant data and context into an intermediate representation (IR), allowing for the determination of column-level lineage relationships. Despite challenges such as dealing with complex SQL statements and nested CTEs, building their own parser has been key in enabling comprehensive column-level lineage support at Metaplane.