ANSI_MODE - Azure Databricks - Databricks SQL

Settings

Follows the SQL standard in how it deals with certain arithmetic operations and type conversions, similar to most databases and data warehouses. Following this standard promotes better data quality, integrity, and portability.

FALSE

Databricks SQL uses Hive-compatible behavior.

You can set this parameter at the session level using the SET statement and at the global level using SQL configuration parameters or Global SQL Warehouses API .

System default

The system default value is TRUE for accounts added on Databricks SQL 2022.35 and later.

Detailed description

The Databricks SQL reference documentation describes SQL standard behavior.

The following sections describe the differences between ANSI_MODE TRUE (ANSI mode) and FALSE (non-ANSI mode).

Operators

In non-ANSI mode, arithmetic operations performed on numeric types may return overflowed values or NULL, while in ANSI mode such operations return an error.

Operator Description Example ANSI_MODE = true ANSI_MODE = false divisor div dividend Returns the integral part of the division of divisor by dividend.


    1 div 0

Error

Functions

The behavior of some built-in functions can be different under ANSI mode vs non-ANSI mode under the conditions specified below.

Operator Description Condition ANSI_MODE = true ANSI_MODE = false element_at(arrayExpr, index) Returns the element of an arrayExpr at index. Invalid array index Error elt(index, expr1 [, …] ) Returns the nth expression. Invalid index Error make_date(y,m,d) Creates a date from year, month, and day fields. Invalid result date Error make_timestamp(y,m,d,h,mi,s[,tz]) Creates a timestamp from fields. Invalid result timestamp Error make_interval(y,m,w,d,h,mi,s) Creates an interval from fields. Invalid result interval Error mod(dividend, divisor) Returns the remainder after dividend / divisor.


    mod(1, 0)

Error next_day(expr,dayOfWeek) Returns the first date which is later than expr and named as in dayOfWeek. Invalid day of week Error parse_url(url, partToExtract[, key]) Extracts a part from url. Invalid URL Error pmod(dividend, divisor) Returns the positive remainder after dividend / divisor.


    pmod(1, 0)

Error size(expr) Returns the cardinality of expr.


    size(NULL)

to_date(expr[,fmt]) Returns expr cast to a date using an optional formatting. Invalid expr or format string Error to_timestamp(expr[,fmt]) Returns expr cast to a timestamp using an optional formatting. Invalid expr or format string Error to_unix_timestamp(expr[,fmt]) Returns the timestamp in expr as a UNIX timestamp. Invalid expr or format string Error unix_timestamp([expr[, fmt]]) Returns the UNIX timestamp of current or specified time. Invalid expr or format string Error

Casting rules

The rules and behaviors regarding CAST are stricter in ANSI mode. They can be divided into the following three categories:

Compile-time conversion rules

Runtime errors

Implicit type coercion rules

Compile-time conversion rules

Source type Target type Example ANSI_MODE = true ANSI_MODE = false

For each of these casts you can use try_cast instead of cast to return NULL rather than of an error.

Implicit type coercion rules

Under ANSI_MODE = TRUE , Databricks SQL uses clear SQL data type casting rules for:

type promotion

downcasting

crosscasting

By contrast ANSI_MODE = FALSE is inconsistent and more lenient. For example:

When using a


    STRING

type with any arithmetic operator, the string is implicitly cast to


    DOUBLE

When comparing a


    STRING

to any numeric type the string is implicitly cast to the type it compares to.

When performing a


    UNION


    COALESCE

, or other operations where a least common type must be found all types are cast to


    STRING

if there is any


    STRING

type present.

Databricks recommends using the explicit cast or try_cast function instead of relying on ANSI_MODE = FALSE .

Examples

> SET ansi_mode = true;
-- Protects against integral numeric overflow
> SELECT cast(12345 AS TINYINT);
  Casting 12345 to tinyint causes overflow
-- For invalid values raises errors instead of returning NULL.
> SELECT cast('a' AS INTEGER);
  Invalid input syntax for type numeric: a.
  To return NULL instead, use 'try_cast'
-- try_cast() is consistent for both modes
> SELECT try_cast('a' AS INTEGER);
-- Does not allow ambiguous crosscasting.
> SELECT c1 + c2 FROM VALUES('5', '7.6') AS T(c1, c2);
  Cannot resolve '(T.c1 + T.c2)' due to data type mismatch:
  '(T.c1 + T.c2)' requires (numeric or interval day to second or interval year to month or interval) type, not string
-- Promotes STRING to least common type (STRING, INTEGER --> BIGINT) for arithmetic operation.
> SELECT typeof(5 - '3');
  bigint
-- Promotes STRING to least common type (INTEGER, STRING --> BIGINT) with runtime check
> SELECT c1 = c2 FROM VALUES(10, '10.1') AS T(c1, c2);
  Invalid input syntax for type numeric: 10.1. To return NULL instead, use 'try_cast'.
-- Promotes STRING to least common type (STRING, INTEGER --> BIGINT) for set operation with runtime check.
> SELECT typeof(c1) FROM (SELECT 5 UNION ALL SELECT '6') AS T(c1);
  bigint
  bigint
> SET ansi_mode = false;
-- Silent integral numeric overflow
> SELECT cast(12345 AS TINYINT);
-- Returns NULL instead of an error
> SELECT cast('a' AS INTEGER);
-- try_cast() is safe for both modes
> SELECT try_cast('a' AS INTEGER);
-- Does allow ambiguous crosscasting using DOUBLE.
> SELECT c1 + c2 FROM VALUES('5', '7.6') AS T(c1, c2);
-- Crosscasts STRING to DOUBLE for arithmetic operation.
> SELECT typeof(5 - '3');
  double
-- Implicitly casts STRING to INTEGER equating 10 with 10.1
> SELECT c1 = c2 FROM VALUES(10, '10.1') AS T(c1, c2);
-- Promotes to string for set operations
> SELECT typeof(c1) FROM (SELECT 5 UNION ALL SELECT '6') AS T(c1);
  string
  string
Related
SQL data type rules
RESET
SET statement
SQL configuration parameters
Global SQL Warehouses API