This topic describes the function that are supported by PolarDB-X 1.0 and some functions that are not supported by this system.
PolarDB-X 1.0 supports the date and time functions, string functions, conversion functions, aggregate functions, mathematical functions, comparison functions, bit functions, flow control functions, information functions, encryption functions, compression functions, and other functions. In addition, JSON functions and geographic information functions can be pushed down and executed.
In the WHERE clause or the UPDATE statement, PolarDB-X 1.0 does not support the following functions: LAST_INSERT_ID(), CONNECTION_ID(), CURRENT_USER(), CURRENT_USER DATABASE(), SCHEMA(), USER(), and VERSION().
PolarDB-X 1.0 does not support the following functions that are supported by MySQL 5.7:
- Full-text search functions
- XML functions
- Global transaction identifier (GTID) functions
- Enterprise encryption functions
The following functions belong to the supported function types. However, these functions are not supported.
| Type | Function | Description |
| Date and time functions | CONVERT_TZ() | Convert from one time zone to another |
| GET_FORMAT() | Return a date format string | |
| LOCALTIME(), LOCALTIME | Synonym for NOW() | |
| LOCALTIMESTAMP, LOCALTIMESTAMP() | Synonym for NOW() | |
| String functions | FIND_IN_SET() | Return the index position of the first argument within the second argument |
| LOAD_FILE() | Load the named file | |
| MATCH | Perform full-text search | |
| SOUNDS LIKE | Compare sounds | |
| Aggregate functions | BIT_AND( | Return bitwise AND |
| BIT_OR() | Return bitwise OR | |
| BIT_XOR() | Return bitwise XOR | |
| GROUP_CONCAT() | Return a concatenated string | |
| STD() | Return the population standard deviation | |
| STDDEV() | Return the population standard deviation | |
| STDDEV_POP() | Return the population standard deviation | |
| STDDEV_SAMP() | Return the sample standard deviation | |
| VAR_POP() | Return the population standard variance | |
| VAR_SAMP() | Return the sample variance | |
| VARIANCE() | Return the population standard variance | |
| Mathematical functions | RADIANS() | Return argument converted to radians |
| Information functions | BENCHMARK() | Repeatedly execute an expression |
| CHARSET() | Return the character set of the argument | |
| COERCIBILITY() | Return the collation coercibility value of the string argument | |
| COLLATION() | Return the collation of the string argument | |
| FOUND_ROWS() | For a SELECT with a LIMIT clause, the number of rows that would be returned were there no LIMIT clause | |
| ROW_COUNT() | The number of rows updated | |
| Encryption functions and compression functions | ASYMMETRIC_DECRYPT() | Decrypt ciphertext using private or public key |
| ASYMMETRIC_DERIVE() | Derive symmetric key from asymmetric keys | |
| ASYMMETRIC_ENCRYPT() | Encrypt cleartext using private or public key | |
| ASYMMETRIC_SIGN() | Generate signature from digest | |
| ASYMMETRIC_VERIFY() | Verify that signature matches digest | |
| CREATE_ASYMMETRIC_PRIV_KEY() | Create private key | |
| CREATE_ASYMMETRIC_PUB_KEY() | Create public key | |
| CREATE_DH_PARAMETERS() | Generate shared DH secret | |
| CREATE_DIGEST() | Generate digest from string | |
| DECODE() (deprecated 5.7.2) | Decodes a string encrypted using ENCODE() | |
| DES_DECRYPT() (deprecated 5.7.6) | Decrypt a string | |
| DES_ENCRYPT() (deprecated 5.7.6) | Encrypt a string | |
| ENCODE() (deprecated 5.7.2) | Encode a string | |
| ENCRYPT() (deprecated 5.7.6) | Encrypt a string | |
| OLD_PASSWORD() | Return the value of the pre-4.1 implementation of PASSWORD | |
| PASSWORD() (deprecated 5.7.6) | Calculate and return a password string | |
| RANDOM_BYTES() | Return a random byte vector | |
| SHA1(), SHA() | Calculate an SHA-1 160-bit checksum | |
| SHA2() | Calculate an SHA-2 checksum | |
| VALIDATE_PASSWORD_STRENGTH() | Determine strength of password | |
| Other functions | ANY_VALUE() | Suppress ONLY_FULL_GROUP_BY value rejection |
| DEFAULT() | Return the default value for a table column | |
| GET_LOCK() | Get a named lock | |
| INET_ATON() | Return the numeric value of an IP address | |
| INET_NTOA() | Return the IP address from a numeric value | |
| INET6_ATON() | Return the numeric value of an IPv6 address | |
| INET6_NTOA() | Return the IPv6 address from a numeric value | |
| IS_FREE_LOCK() | Whether the named lock is free | |
| IS_IPV4() | Whether argument is an IPv4 address | |
| IS_IPV4_COMPAT() | Whether argument is an IPv4-compatible address | |
| IS_IPV4_MAPPED() | Whether argument is an IPv4-mapped address | |
| IS_IPV6() | Whether argument is an IPv6 address | |
| IS_USED_LOCK() | Whether the named lock is in use; return connection identifier if true | |
| MASTER_POS_WAIT() | Block until the slave has read and applied all updates up to the specified position | |
| NAME_CONST() | Causes the column to have the given name |