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Connectors and APIs Manual  /  ...  /  Connector/NET Connection Options Reference

4.4.5 Connector/NET Connection Options Reference

This chapter describes the full set of MySQL Connector/NET 8.0 connection options. The protocol you use to make a connection to the server (classic MySQL protocol or X Protocol) determines which options you should use. Connection options have a default value that you can override by defining the new value in the connection string (classic MySQL protocol and X Protocol) or in the URI-like connection string (X Protocol). Connector/NET option names and synonyms are not case sensitive.

For instructions about how to use connection strings, see Section 4.4.1, “Creating a Connector/NET Connection String”. For alternative connection styles, see Connecting to the Server Using URI-Like Strings or Key-Value Pairs.

The following sections list the connection options that apply to both protocols, classic MySQL protocol only, and X Protocol only:

Options for Both Classic MySQL Protocol and X Protocol

The following Connector/NET connection options can be used with either protocol. Connector/NET 8.0 exposes the options in this section as properties in both the MySql.Data.MySqlClient.MySqlConnectionStringBuilder and MySqlX.XDevAPI.MySqlXConnectionStringBuilder classes.

CertificateFile , Certificate File

Default: null

This option specifies the path to a certificate file in PKCS #12 format (.pfx). For an example of usage, see Section, “Using PFX Certificates in Connector/NET”.

CertificatePassword , Certificate Password

Default: null

Specifies a password that is used in conjunction with a certificate specified using the option CertificateFile. For an example of usage, see Section, “Using PFX Certificates in Connector/NET”.

CertificateStoreLocation , Certificate Store Location

Default: null

Enables you to access a certificate held in a personal store, rather than use a certificate file and password combination. For an example of usage, see Section, “Using PFX Certificates in Connector/NET”.

CertificateThumbprint , Certificate Thumbprint

Default: null

Specifies a certificate thumbprint to ensure correct identification of a certificate contained within a personal store. For an example of usage, see Section, “Using PFX Certificates in Connector/NET”.

CharacterSet , Character Set , CharSet

Specifies the character set that should be used to encode all queries sent to the server. Results are still returned in the character set of the result data.

ConnectionProtocol , Protocol , Connection Protocol

Default: socket (or tcp)

Specifies the type of connection to make to the server. Values can be:

  • socket or tcp for a socket connection using TCP/IP.

  • pipe for a named pipe connection (not supported with X Protocol).

  • unix for a UNIX socket connection.

  • memory to use MySQL shared memory (not supported with X Protocol).

Database , Initial Catalog

Default: mysql

The case-sensitive name of the database to use initially.

dns-srv , dnssrv

Default: false

Enables the connection to resolve service (SRV) addresses in a DNS SRV record, which defines the location (host name and port number) of servers for the specified services when it is used with the default transport protocol (tcp). A single DNS domain can map to multiple targets (servers) using SRV address records. Each SRV record includes the host name, port, priority, and weight. DNS SRV support was introduced in Connector/NET 8.0.19 to remove the need for clients to identify each possible host in the connection string, with or without connection pooling.

Specifying multiple host names, a port number, or a Unix socket, named pipe, or shared memory connection (see the ConnectionProtocol option) in the connection string is not permitted when DNS SRV is enabled.

Using classic MySQL protocol.  The dns-srv option applies to connection strings; the DnsSrv property is declared in the MySqlConnectionStringBuilder class.

// Connection string example
 var conn = new MySqlConnection(";
                                 user id=user;

// MySqlConnectionStringBuilder class example
 var sb = new MySqlConnectionStringBuilder();
  Server = "",
  UserID = "user",
  Password = "****",
  DnsSrv = true,
  Database = "test"

var conn = new MySqlConnection(sb.ConnectionString);

Using X Protocol.  The dns-srv option applies to connection strings and anonymous objects. The DnsSrv property is declared in the MySqlXConnectionStringBuilder class. An error is raised if both dns-srv=false and the URI scheme of mysqlx+srv:// are combined to create a conflicting connection configuration. For details about using the mysqlx+srv:// scheme element in URI-like connection strings, see Connections Using DNS SRV Records.

// Connection string example

var session = MySQLX.GetSession(";
                                 user id=user;

// Anonymous object example

var connstring = new
  server = "",
  user = "user",
  password = "****",
  dnssrv = true

var session = MySQLX.GetSession(connString);

// MySqlXConnectionStringBuilder class example

var sb = new MySqlXConnectionStringBuilder();
  Server = "",
  UserID = "user",
  Password = "****",
  DnsSrv = true,
  Database = "test"

var session = MySQLX.GetSession(sb.ConnectionString);
Keepalive , Keep Alive

Default: 0

For TCP connections, idle connection time measured in seconds, before the first keepalive packet is sent. A value of 0 indicates that keepalive is not used. Before Connector/NET 6.6.7/6.7.5/6.8.4, this value was measured in milliseconds.

Password , Password1 , pwd , pwd1

Default: an empty string

The password for the MySQL account being used for one-factor/single-factor authentication (1FA/SFA), which uses only one authentication method such as a password.

Starting with Connector/NET 8.0.28, this option also provides the first secret password for an account that has multiple authentication factors. The server can require one (1FA), two (2FA), or three (3FA) passwords to authenticate the MySQL account. For example, if an account with 2FA is created as follows:

CREATE USER 'abe'@'localhost'
  IDENTIFIED WITH caching_sha2_password
    BY 'sha2_password'
  AND IDENTIFIED WITH authentication_ldap_sasl
    AS 'uid=u1_ldap,ou=People,dc=example,dc=com';

Then your application can specify a connection string with this option (password or its synonyms) and a value, sha2_password in this case, to satisfy the first authentication factor.

var connString =  "server=localhost;

Alternatively, for a connection made using the MySqlConnectionStringBuilder object:

MySqlConnectionStringBuilder settings = new MySqlConnectionStringBuilder()
       Server = "localhost", 
       UserID = "abe",
       Pwd1 = "sha2_password",
       Pwd2 = "ldap_password",
       Port = 3306

If the server does not require a secret password be used with an authentication method, then the value specified for the password, password2, or password3 option is ignored.

Password2 , pwd2

Default: an empty string

The second secret password for an account that has multiple authentication factors (see the Password connection option).

Password3 , pwd3

Default: an empty string

The third secret password for an account that has multiple authentication factors (see the Password connection option).


Default: 3306

The port MySQL is using to listen for connections. This value is ignored if Unix socket is used.

Server , Host , Data Source , DataSource

Default: localhost

The name or network address of one or more host computers. Multiple hosts are separated by commas and a priority (0 to 100), if provided, determines the host selection order. As of Connector/NET 8.0.19, host selection is random when priorities are omitted or are the same for each host.

// Selects the host with the highest priority (100) first

No attempt is made by the provider to synchronize writes to the database, so take care when using this option. In UNIX environments with Mono, this can be a fully qualified path to a MySQL socket file. With this configuration, the UNIX socket is used instead of the TCP/IP socket. Currently, only a single socket name can be given, so accessing MySQL in a replicated environment using UNIX sockets is not currently supported.

SslCa , Ssl-Ca

Default: null

Based on the type of certificates being used, this option either specifies the path to a certificate file in PKCS #12 format (.pfx) or the path to a file in PEM format (.pem) that contains a list of trusted SSL certificate authorities (CA).

With PFX certificates in use, this option engages when the SslMode connection option is set to a value of Required, VerifyCA, or VerifyFull; otherwise, it is ignored.

With PEM certificates in use, this option engages when the SslMode connection option is set to a value of VerifyCA or VerifyFull; otherwise, it is ignored.

For examples of usage, see Section, “Using PEM Certificates in Connector/NET”.

SslCert , Ssl-Cert

Default: null

The name of the SSL certificate file in PEM format to use for establishing an encrypted connection. This option engages only when VerifyFull is set for the SslMode connection option and the SslCa connection option uses a PEM certificate; otherwise, it is ignored. For an example of usage, see Section, “Using PEM Certificates in Connector/NET”.

SslKey , Ssl-Key

Default: null

The name of the SSL key file in PEM format to use for establishing an encrypted connection. This option engages only when VerifyFull is set for the SslMode connection option and the SslCa connection option uses a PEM certificate; otherwise, it is ignored. For an example of usage, see Section, “Using PEM Certificates in Connector/NET”.

SslMode , Ssl Mode , Ssl-Mode

Default: Depends on the version of Connector/NET and the protocol in use. Named-pipe and shared-memory connections are not supported with X Protocol.

  • Required for 8.0.8 to 8.0.12 (both protocols); 8.0.13 and later (X Protocol only).

  • Preferred for 8.0.13 and later (classic MySQL protocol only).

This option has the following values:

  • Disabled – Do not use SSL. Non-SSL enabled servers require this option be set to Disabled explicitly for Connector/NET 8.0.29 or later.

  • None – Do not use SSL. Non-SSL enabled servers require this option be set to None explicitly for Connector/NET 8.0.8 or later.


    This value is deprecated starting with Connector/NET 8.0.29. Use Disabled instead.

  • Preferred – Use SSL if the server supports it, but allow connection in all cases. This option was removed in Connector/NET 8.0.8 and reimplemented in 8.0.13 for classic MySQL protocol only.


    Do not use this option for X Protocol operations.

  • Required – Always use SSL. Deny connection if server does not support SSL.

  • VerifyCA – Always use SSL. Validate the certificate authorities (CA), but tolerate a name mismatch.

  • VerifyFull – Always use SSL. Fail if the host name is not correct.

tlsversion , tls-version , tls version

Default: A fallback solution decides which version of TLS to use.

Restricts the set of TLS protocol versions to use during the TLS handshake when both the client and server support the TLS versions indicated and the value of the SslMode connection-string option is not set to Disabled or None (deprecated in Connector/NET 8.0.29). This option accepts a single version or a list of versions separated by a comma, for example, tls-version=TLSv1.2, TLSv1.3;.

Connector/NET supports the following values:

  • TLSv1.3

  • TLSv1.2

An error is reported when a value other than those listed is assigned. Likewise, an error is reported when an empty list is provided as the value, or if all of the versions in the list are unsupported and no connection attempt is made.

UserID , User Id , Username , Uid , User name , User

Default: null

The MySQL login account being used.

Options for Classic MySQL Protocol Only

Options related to systems using a connection pool appear together at the end of the list of general options (see Connection-Pooling Options). Connector/NET 8.0 exposes the options in this section as properties in the MySql.Data.MySqlClient.MySqlConnectionStringBuilder class.

General Options.  The Connector/NET options that follow are for general use with connection strings and the options apply to all MySQL server configurations:

AllowBatch , Allow Batch

Default: true

When true, multiple SQL statements can be sent with one command execution. Batch statements should be separated by the server-defined separator character.

AllowLoadLocalInfile , Allow Load Local Infile

Default: false

Disables (by default) or enables the server functionality to load the data local infile. If this option is set to true, uploading files from any location is enabled, regardless of the path specified with the AllowLoadLocalInfileInPath option.

AllowLoadLocalInfileInPath , Allow Load Local Infile In Path

Default: null

Specifies a safe path from where files can be read and uploaded to the server. When the related AllowLoadLocalInfile option is set to false, which is the default value, only those files from the safe path or any valid subfolder specified with the AllowLoadLocalInfileInPath option can be loaded. For example, if /tmp is set as the restricted folder, then file requests for /tmp/myfile and /tmp/myfolder/myfile can succeed. No relative paths or symlinks that fall outside of this path are permitted.

The following table shows the behavior that results when the AllowLoadLocalInfile and AllowLoadLocalInfileInPath connection string options are combined.

AllowLoadLocalInfile Value AllowLoadLocalInfileInPath Value Behavior
true Empty string or null value All uploads are permitted.
true A valid path All uploads are permitted (the path is not respected).
false Empty string or null value No uploads are permitted.
false A valid path Only uploads from the specified folder and subfolder are permitted.

Default: false

Setting this option to true informs Connector/NET that RSA public keys should be retrieved from the server and that connections using the classic MySQL protocol, when SSL is disabled, will fail by default. Exceptions to the default behavior can occur when previous successful connection attempts were made or when pooling is enabled and a pooled connection can be reused. This option was introduced with the 8.0.10 connector.


This option is prone to man-in-the-middle attacks, so it should be used only in situations where you can ensure by other means that your connections are made to trusted servers.

AllowUserVariables , Allow User Variables

Default: false

Setting this to true indicates that the provider expects user variables in the SQL.

AllowZeroDateTime , Allow Zero Datetime

Default: false

If set to True, MySqlDataReader.GetValue() returns a MySqlDateTime object for date or datetime columns that have disallowed values, such as zero datetime values, and a System.DateTime object for valid values. If set to False (the default setting) it causes a System.DateTime object to be returned for all valid values and an exception to be thrown for disallowed values, such as zero datetime values.

AutoEnlist , Auto Enlist

Default: true

If AutoEnlist is set to true, which is the default, a connection opened using TransactionScope participates in this scope, it commits when the scope commits and rolls back if TransactionScope does not commit. However, this feature is considered security sensitive and therefore cannot be used in a medium trust environment.

As of 8.0.10, this option is supported in .NET Core 2.0 implementations.


Default: null

A POSIX-style regular expression that matches the names of BLOB columns that do not contain UTF-8 character data. See Section 4.5.16, “Character Set Considerations for Connector/NET” for usage details.


Default: null

A POSIX-style regular expression that matches the names of BLOB columns containing UTF-8 character data. See Section 4.5.16, “Character Set Considerations for Connector/NET” for usage details.

CheckParameters , Check Parameters

Default: true

Indicates if stored routine parameters should be checked against the server.

CommandInterceptors , Command Interceptors

The list of interceptors that can intercept SQL command operations.

ConnectionTimeout , Connect Timeout , Connection Timeout

Default: 15

The length of time (in seconds) to wait for a connection to the server before terminating the attempt and generating an error.

ConvertZeroDateTime , Convert Zero Datetime

Default: false

Use true to have MySqlDataReader.GetValue() and MySqlDataReader.GetDateTime() return DateTime.MinValue for date or datetime columns that have disallowed values.


Takes precedence over the server-side default authentication plugin when a valid authentication plugin is specified (see Section 4.4.4, “Connector/NET Authentication”). The Defaultauthenticationplugin option is mandatory for supporting userless and passwordless Kerberos authentications in which the credentials are retrieved from a cache or the Key Distribution Center (KDC). For example:

MySqlConnectionStringBuilder settings = new MySqlConnectionStringBuilder()
       Server = "localhost", 
       UserID = "",
       Password = "",
       Database = "mydb",
       Port = 3306,
       DefaultAuthenticationPlugin = "authentication_kerberos_client"

If no value is set, the server-side default authentication plugin is used.

This option was introduced with the 8.0.26 connector.

DefaultCommandTimeout , Default Command Timeout

Default: 30

Sets the default value of the command timeout to be used. This does not supersede the individual command timeout property on an individual command object. If you set the command timeout property, that will be used.

DefaultTableCacheAge , Default Table Cache Age

Default: 60

Specifies how long a TableDirect result should be cached, in seconds. For usage information about table caching, see Section 4.5.3, “Using Connector/NET with Table Caching”.

ExceptionInterceptors , Exception Interceptors

The list of interceptors that can triage thrown MySqlException exceptions.

FunctionsReturnString , Functions Return String

Default: false

Causes the connector to return binary or varbinary values as strings, if they do not have a table name in the metadata.

Includesecurityasserts , Include security asserts

Default: false

Must be set to true when using the MySQLClientPermissions class in a partial trust environment, with the library installed in the GAC of the hosting environment. See Section 4.5.7, “Working with Partial Trust / Medium Trust” for details.

As of 8.0.10, this option is supported in .NET Core 2.0 implementations.

InteractiveSession , Interactive , Interactive Session

Default: false

If set to true, the client is interactive. An interactive client is one in which the server variable CLIENT_INTERACTIVE is set. If an interactive client is set, the wait_timeout variable is set to the value of interactive_timeout. The client session then times out after this period of inactivity. For more information, see Server System Variables in the MySQL Reference Manual.

As of 8.0.10, this option is supported in .NET Core 2.0 implementations.

IntegratedSecurity , Integrated Security

Default: no

Use Windows authentication when connecting to server. By default, it is turned off. To enable, specify a value of yes. (You can also use the value sspi as an alternative to yes.) For details, see Section 4.4.4, “Connector/NET Authentication”.

Currently not supported for .NET Core implementations.

KerberosAuthMode , kerberos auth mode

Default: AUTO

On Windows, provides authentication support using Security Support Provider Interface (SSPI), which is capable of acquiring credentials from the Windows in-memory cache, and Generic Security Service Application Program Interface (GSSAPI) through the MIT Kerberos library. GSSAPI is capable of acquiring cached credentials previously generated using the kinit command. The default value for this option (AUTO) attempts to authenticate with GSSAPI if the authentication using SSPI fails.


This option is permitted in Windows environments only. Using it in non-Windows environments produces an Option not supported exception.

Possible values for this connection option are:

  • AUTO – Use SSPI and fall back to GSSAPI in case of failure.

  • SSPI – Use SSPI only and raise an exception in case of failure.

  • GSSAPI – Use GSSAPI only and raise an exception in case of failure. Always use the KRB5_CONFIG and KRB5CCNAME environment variables to specify configuration and cache locations when using GSSAPI through the MIT Kerberos library on Windows.


Default: false

When the value is set to true, various pieces of information are sent to all configured trace listeners. For a more detailed description, see Section 4.5.12, “Connector/NET Tracing”.

As of 8.0.10, this option is supported in .NET Core 2.0 implementations.

ociConfigFile , OCI Config File

Defaults to one of the following path names:

  • ~/.oci/config on Linux and macOS host types

  • %HOMEDRIVE%%HOMEPATH%\.oci\config on Windows host types

If set, this option specifies an alternative location to the Oracle Cloud Infrastructure configuration file. Connector/NET 8.0.27 (and later) uses the Oracle Cloud Infrastructure SDK to obtain a fingerprint of the API key to use for authentication (fingerprint entry) and location of a PEM file with the private part of the API key (key_file entry). The entries should be specified in the [DEFAULT] profile. If the [DEFAULT] profile is missing from the configuration file, Connector/NET locates the next profile to use instead.

Not supported for .NET Framework 4.5.x implementations.

OciConfigProfile , OCI Config Profile

If set in Connector/NET 8.0.33 (or later), this option specifies which profile in an Oracle Cloud Infrastructure configuration file to use. The profile value defaults to the DEFAULT profile when no value is provided.

Not supported for .NET Framework 4.5.x implementations.

OldGuids , Old Guids

Default: false

The back-end representation of a GUID type was changed from BINARY(16) to CHAR(36). This was done to allow developers to use the server function UUID() to populate a GUID table - UUID() generates a 36-character string. Developers of older applications can add 'Old Guids=true' to the connection string to use a GUID of data type BINARY(16).


Default: false

As of Connector/NET 8.3.0, calling the MySqlDataReader.GetString() method throws an InvalidCastException exception if the column is not a string type. All text types including char and varchar are allowed; and blob is not considered a text type.

Setting this OldGetStringBehavior connection option to true restores previous behavior by logging a deprecation warning instead of throwing the exception.

This option was added in 8.3.0 and removed in 9.0.0.

PersistSecurityInfo , Persist Security Info

Default: false

When set to false or no (strongly recommended), security-sensitive information, such as the password, is not returned as part of the connection if the connection is open or has ever been in an open state. Resetting the connection string resets all connection string values, including the password. Recognized values are true, false, yes, and no.

PipeName , Pipe Name , Pipe

Default: mysql

When set to the name of a named pipe, the MySqlConnection attempts to connect to MySQL on that named pipe. This setting only applies to the Windows platform.


For MySQL 8.0.14 and later, 5.7.25 and later, and 5.6.43 and later, minimal permissions on named pipes are granted to clients that use them to connect to the server. However, Connector/NET can use named pipes only when granted full access on them. As a workaround, create a Windows local group containing the user that executes the client application. Restart the target server with the named_pipe_full_access_group system variable and specify the local group name as its value.

Currently not supported for .NET Core implementations.

ProcedureCacheSize , Procedure Cache Size , procedure cache , procedurecache

Default: 25

Sets the size of the stored procedure cache. By default, Connector/NET stores the metadata (input/output data types) about the last 25 stored procedures used. To disable the stored procedure cache, set the value to zero (0).


Default: false

Indicates if this connection is to use replicated servers.

As of 8.0.10, this option is supported in .NET Core 2.0 implementations.

RespectBinaryFlags , Respect Binary Flags

Default: true

Setting this option to false means that Connector/NET ignores a column's binary flags as set by the server.

SharedMemoryName , Shared Memory Name

Default: mysql

The name of the shared memory object to use for communication if the transport protocol is set to memory. This setting only applies to the Windows platform.

Currently not supported for .NET Core implementations.

SqlServerMode , Sql Server Mode

Default: false

Allow SQL Server syntax. When set to true, enables Connector/NET to support square brackets around symbols instead of backticks. This enables Visual Studio wizards that bracket symbols between the [ and ] characters to work with Connector/NET. This option incurs a performance hit, so should only be used if necessary.

TableCaching , Table Cache , TableCache

Default: false

Enables or disables caching of TableDirect commands. A value of true enables the cache while false disables it. For usage information about table caching, see Section 4.5.3, “Using Connector/NET with Table Caching”.

TreatBlobsAsUTF8 , Treat BLOBs as UTF8

Default: false

Setting this value to true causes BLOB columns to have a character set of utf8 with the default collation for that character set. To convert only some of your BLOB columns, you can make use of the 'BlobAsUTF8IncludePattern' and 'BlobAsUTF8ExcludePattern' keywords. Set these to a regular expression pattern that matches the column names to include or exclude respectively.

TreatTinyAsBoolean , Treat Tiny As Boolean

Default: true

Setting this value to false causes TINYINT(1) to be treated as an INT. See Numeric Data Type Syntax for a further explanation of the TINYINT and BOOL data types.

UseAffectedRows , Use Affected Rows

Default: false

When true, the connection reports changed rows instead of found rows.

UseCompression , Compress , Use Compression

Default: false

Setting this option to true enables compression of packets exchanged between the client and the server. This exchange is defined by the MySQL client/server protocol.

Compression is used if both client and server support ZLIB compression, and the client has requested compression using this option.

A compressed packet header is: packet length (3 bytes), packet number (1 byte), and Uncompressed Packet Length (3 bytes). The Uncompressed Packet Length is the number of bytes in the original, uncompressed packet. If this is zero, the data in this packet has not been compressed. When the compression protocol is in use, either the client or the server may compress packets. However, compression will not occur if the compressed length is greater than the original length. Thus, some packets will contain compressed data while other packets will not.

UseDefaultCommandTimeoutForEF , Use Default Command Timeout For EF

Default: false

Enforces the command timeout of EFMySqlCommand, which is set to the value provided by the DefaultCommandTimeout property.

UsePerformanceMonitor , Use Performance Monitor , UserPerfMon , PerfMon

Default: false

Indicates that performance counters should be updated during execution.

Currently not supported for .NET Core implementations.

UseUsageAdvisor , Use Usage Advisor , Usage Advisor

Default: false

Logs inefficient database operations.

As of 8.0.10, this option is supported in .NET Core 2.0 implementations.

Connection-Pooling Options.  The following options are related to connection pooling within connection strings. For more information about connection pooling, see Opening a Connection to a Single Server.

CacheServerProperties , Cache Server Properties

Default: false

Specifies whether server variable settings are updated by a SHOW VARIABLES command each time a pooled connection is returned. Enabling this setting speeds up connections in a connection pool environment. Your application is not informed of any changes to configuration variables made by other connections.

ConnectionLifeTime , Connection Lifetime

Default: 0

When a connection is returned to the pool, its creation time is compared with the current time and the connection is destroyed if that time span (in seconds) exceeds the value specified by Connection Lifetime. This option is useful in clustered configurations to force load balancing between a running server and a server just brought online. A value of zero (0) sets pooled connections to the maximum connection timeout.

ConnectionReset , Connection Reset

Default: false

If true, the connection state is reset when it is retrieved from the pool. The default value of false avoids making an additional server round trip when obtaining a connection, but the connection state is not reset.

MaximumPoolsize , Max Pool Size , Maximum Pool Size , MaxPoolSize

Default: 100

The maximum number of connections allowed in the pool.

MinimumPoolSize , Min Pool Size , Minimum Pool Size , MinPoolSize

Default: 0

The minimum number of connections allowed in the pool.


Default: true

When true, the MySqlConnection object is drawn from the appropriate pool, or if necessary, is created and added to the appropriate pool. Recognized values are true, false, yes, and no.

Options for X Protocol Only

The connection options that follow are valid for connections made with X Protocol. Connector/NET 8.0 exposes the options in this section as properties in the MySqlX.XDevAPI.MySqlXConnectionStringBuilder class.

Auth , Authentication , Authentication Mode

Authentication mechanism to use with the X Protocol. This option was introduced with the 8.0.9 connector and has the following values, which are not case-sensitive: MYSQL41, PLAIN, and EXTERNAL. If the Auth option is not set, the mechanism is chosen depending on the connection type. PLAIN is used for secure connections (TLS or Unix sockets) and MYSQL41 is used for unencrypted connections. EXTERNAL is used for external authentication methods such as PAM, Windows login IDs, LDAP, or Kerberos. (EXTERNAL is not currently supported.)

The Auth option is not supported for classic MySQL protocol connections and returns NotSupportedException if used.

Compression , use-compression

Default: preferred

Compression is used to send and receive data when both the client and server support it for X Protocol connections and the client requests compression using this option. After a successful algorithm negotiation is made, Connector/NET can start compressing data immediately. To prevent the compression of small data packets, or of data already compressed, Connector/NET defines a size threshold of 1000 bytes.

When multiple compression algorithms are supported by the server, Connector/NET applies the following priority by default: zstd_stream (first), lz4_message (second), and deflate_stream (third). The deflate_stream algorithm is supported for use with .NET Core, but not for .NET Framework.


Use the compression-algorithms option to specify one ore more supported algorithms in a different order. The algorithms are negotiated in the order provided by client. For usage details, see the compression-algorithms option.

Data compression for X Protocol connections was added in the Connector/NET 8.0.20 release. The Compression option accepts the following values:

  • preferred to apply data compression if the server supports the algorithms chosen by the client. Otherwise, the data is sent and received without compression.

  • required to ensure that compression is used or to terminate the connection and return an error message.

  • disabled to prevent data compression.

compression-algorithms , CompressionAlgorithms

As of Connector/NET 8.0.22, a client application can specify the order in which supported compression algorithms are negotiated with the server. The value of the Compression connection option must be set to preferred or to required for this option to apply. Unsupported algorithms are ignored.

This option accepts the following algorithm names and synonyms:

  • lz4_message or lz4

  • zstd_stream or zstd

  • deflate_stream or deflate (not valid with .NET Framework)

Algorithm names and synonyms can be combined in a comma-separated list or provided as a standalone value (with or without brackets). Examples:

// Compression option set to preferred (default)

// Compression option set to required

// Connection string

// Anonymous object
MySQLX.GetSession(new { 
   server = "localhost", 
   port = "3306", 
   uid = "test", 
   password = "test", 
   compressionalgorithms = "deflate_stream" })

For additional information, see Connection Compression with X Plugin.

connection-attributes , ConnectionAttributes

Default: true

This option was introduced in Connector/NET 8.0.16 for submitting a set of attributes to be passed together with default connection attributes to the server. The aggregate size of connection attribute data sent by a client is limited by the value of the performance_schema_session_connect_attrs_size server variable. The total size of the data package should be less than the value of the server variable. For general information about connection attributes, see Performance Schema Connection Attribute Tables.

The connection-attributes parameter value can be empty (the same as specifying true), a Boolean value (true or false to enable or disable the default attribute set), or a list or zero or more key=value specifiers separated by commas (to be sent in addition to the default attribute set). Within a list, a missing key value evaluates as the NULL value. Examples:

// Sessions

// Pooling

Application-defined attribute names cannot begin with _ because such names are reserved for internal attributes.

If connection attributes are not specified in a valid way, an error occurs and the connection attempt fails.

Connect-Timeout , ConnectTimeout

Default: 10000

The length of time (in milliseconds) to wait for an X Protocol connection to the server before terminating the attempt and generating an error. You can disable the connection timeout by setting the value to zero. This option can be specified as follows:

  • URI-like connection string example

  • Connection string example

  • Anonymous object example

    MySQLX.GetSession(new { server="localhost", user="test", port=33060, connecttimeout=2000 });
  • MySqlXConnectionStringBuilder class example

    var builder = new MySqlXConnectionStringBuilder("server=localhost;user=test;port=33060");
    builder.ConnectTimeout = 2000;
SslCrl , Ssl-Crl

Default: null

Path to a local file containing certificate revocation lists.


Although the SslCrl connection-string option is valid for use, applying it raises a NotSupportedException message.