[ES-1877316] Promote Float(precision>24) to DOUBLE in CREATE TABLE#65
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[ES-1877316] Promote Float(precision>24) to DOUBLE in CREATE TABLE#65jayantsing-db wants to merge 1 commit into
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SQLAlchemy's default visit_float drops the precision argument when rendering for Databricks (no FLOAT(p) form exists), so Float(precision=53) silently compiled to a 32-bit FLOAT column. pandas.DataFrame.to_sql maps float64 to Float(precision=53), so every to_sql round-trip of a float64 column was being permanently truncated at the CREATE TABLE step — no way to recover the lost bits later, even after the INSERT-side fix in databricks-sql-python v4.2.6. Add a @compiles(Float, "databricks") that promotes to DOUBLE when precision > 24, matching the SQL-standard cutover from single to double precision. Float() without precision keeps the current FLOAT behavior; sqlalchemy.types.FLOAT (uppercase, explicit 32-bit) and sqlalchemy.types.Double are unaffected because they have their own __visit_name__. Co-authored-by: Isaac Signed-off-by: Jayant Singh <jayant.singh@databricks.com>
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SQLAlchemy's default visit_float drops the precision argument when rendering for Databricks (no FLOAT(p) form exists), so Float(precision=53) silently compiled to a 32-bit FLOAT column. pandas.DataFrame.to_sql maps float64 to Float(precision=53), so every to_sql round-trip of a float64 column was being permanently truncated at the CREATE TABLE step — no way to recover the lost bits later, even after the INSERT-side fix in databricks-sql-python v4.2.6.
Add a
@compiles(Float, "databricks")that promotes to DOUBLE when precision > 24, matching the SQL-standard cutover from single to double precision. Float() without precision keeps the current FLOAT behavior; sqlalchemy.types.FLOAT (uppercase, explicit 32-bit) and sqlalchemy.types.Double are unaffected because they have their own visit_name.Co-authored-by: Isaac