> ## Documentation Index > Fetch the complete documentation index at: https://docs.firebolt.io/llms.txt > Use this file to discover all available pages before exploring further. # String functions > BigQuery string and regular expression functions supported in BigQuery compatibility mode. Preview BigQuery [string functions](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions) in [BigQuery compatibility mode](/compatibility-modes/bigquery/overview). Support is one of: Supported, With limitations, or Not supported. Supported means the function is available in BigQuery mode; where Firebolt's behavior differs from BigQuery, it is noted. | Function | Support | Notes | | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | :--------------- | :----------------------------------------------------------------------------------------------- | | [`ASCII`](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions#ascii) | Supported | | | [`BYTE_LENGTH`](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions#byte_length) | Supported | | | [`CHAR_LENGTH`](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions#char_length) | Supported | | | [`CHARACTER_LENGTH`](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions#character_length) | Supported | | | [`CONCAT`](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions#concat) | Supported | | | [`CONTAINS_SUBSTR`](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions#contains_substr) | Supported | | | [`FORMAT`](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions#format_string) | With limitations | Available, but format-specifier behavior may differ from BigQuery. | | [`FROM_HEX`](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions#from_hex) | Supported | | | [`INSTR`](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions#instr) | With limitations | Two-argument form only. Position and occurrence arguments are not supported. | | [`LEFT`](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions#left) | Supported | | | [`LENGTH`](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions#length) | Supported | | | [`LOWER`](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions#lower) | Supported | | | [`LPAD`](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions#lpad) | Supported | | | [`LTRIM`](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions#ltrim) | Supported | | | [`OCTET_LENGTH`](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions#octet_length) | Supported | | | [`REGEXP_CONTAINS`](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions#regexp_contains) | Supported | RE2 syntax. | | [`REGEXP_EXTRACT`](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions#regexp_extract) | With limitations | Whole-match and single-capture-group forms. Position and occurrence arguments are not supported. | | [`REGEXP_EXTRACT_ALL`](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions#regexp_extract_all) | Supported | | | [`REGEXP_REPLACE`](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions#regexp_replace) | Supported | | | [`REPEAT`](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions#repeat) | Supported | | | [`REPLACE`](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions#replace) | Supported | | | [`REVERSE`](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions#reverse) | Supported | | | [`RIGHT`](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions#right) | Supported | | | [`RPAD`](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions#rpad) | Supported | | | [`RTRIM`](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions#rtrim) | Supported | | | [`SOUNDEX`](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions#soundex) | Supported | | | [`SPLIT`](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions#split) | Supported | Delimiter defaults to a comma. | | [`STARTS_WITH`](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions#starts_with) | Supported | | | [`STRPOS`](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions#strpos) | Supported | | | [`SUBSTR`](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions#substr) | Supported | | | [`SUBSTRING`](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions#substring) | Supported | | | [`TO_HEX`](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions#to_hex) | Supported | | | [`TRIM`](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions#trim) | Supported | | | [`UPPER`](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/string_functions#upper) | Supported | | | `CHR`, `CODE_POINTS_TO_BYTES`, `CODE_POINTS_TO_STRING`, `COLLATE`, `EDIT_DISTANCE`, `ENDS_WITH`, `FROM_BASE32`, `FROM_BASE64`, `INITCAP`, `NORMALIZE`, `NORMALIZE_AND_CASEFOLD`, `REGEXP_INSTR`, `REGEXP_SUBSTR`, `SAFE_CONVERT_BYTES_TO_STRING`, `TO_BASE32`, `TO_BASE64`, `TO_CODE_POINTS`, `TRANSLATE`, `UNICODE` | Not supported | |