Documentation ¶
Index ¶
- Constants
- Variables
- type Coercibility
- type Environment
- func (env *Environment) AllCollationIDs() []ID
- func (env *Environment) BinaryCollationForCharset(charset string) ID
- func (cached *Environment) CachedSize(alloc bool) int64
- func (env *Environment) CharsetAlias(charset string) (alias string, ok bool)
- func (env *Environment) CollationAlias(collation string) (string, bool)
- func (env *Environment) DefaultCollationForCharset(charset string) ID
- func (env *Environment) DefaultConnectionCharset() ID
- func (env *Environment) EnsureCollate(fromID, toID ID) error
- func (env *Environment) IsSupported(coll ID) bool
- func (env *Environment) LookupByCharset(name string) *colldefaults
- func (env *Environment) LookupByName(name string) ID
- func (env *Environment) LookupCharsetName(coll ID) string
- func (env *Environment) LookupID(name string) (ID, bool)
- func (env *Environment) LookupName(id ID) string
- func (env *Environment) ParseConnectionCharset(csname string) (ID, error)
- type ID
- type Repertoire
- type TypedCollation
Constants ¶
const ( CollationUtf8mb3ID = 33 CollationUtf8mb4ID = 255 CollationBinaryID = 63 CollationUtf8mb4BinID = 46 CollationLatin1Swedish = 8 )
A few interesting character set values. See http://dev.mysql.com/doc/internals/en/character-set.html#packet-Protocol::CharacterSet
Variables ¶
var SystemCollation = TypedCollation{ Collation: CollationUtf8mb3ID, Coercibility: CoerceCoercible, Repertoire: RepertoireUnicode, }
SystemCollation is the default collation for the system tables such as the information schema. This is still utf8mb3 to match MySQLs behavior. This means that you can't use utf8mb4 in table names, column names, without running into significant issues.
Functions ¶
This section is empty.
Types ¶
type Coercibility ¶
type Coercibility byte
Coercibility is a numeric value that represents the precedence of a collation when applied to a SQL expression. When trying to coerce the collations of two different expressions so that they can be compared, the expression with the lowest coercibility value will win and its collation will be forced upon the other expression.
The rules for assigning a Coercibility value to an expression are as follows:
- An explicit COLLATE clause has a coercibility of 0 (not coercible at all).
- The concatenation of two strings with different collations has a coercibility of 1.
- The collation of a column or a stored routine parameter or local variable has a coercibility of 2.
- A “system constant” (the string returned by functions such as USER() or VERSION()) has a coercibility of 3.
- The collation of a literal has a coercibility of 4.
- The collation of a numeric or temporal value has a coercibility of 5.
- NULL or an expression that is derived from NULL has a coercibility of 6.
According to the MySQL documentation, Coercibility is an actual word of the English language, although the Vitess maintainers disagree with this assessment.
See: https://dev.mysql.com/doc/refman/8.0/en/charset-collation-coercibility.html
const ( CoerceExplicit Coercibility = iota CoerceNone CoerceImplicit CoerceSysconst CoerceCoercible CoerceNumeric CoerceIgnorable )
func (Coercibility) String ¶
func (ci Coercibility) String() string
type Environment ¶
type Environment struct {
// contains filtered or unexported fields
}
Environment is a collation environment for a MySQL version, which contains a database of collations and defaults for that specific version.
func MySQL8 ¶ added in v0.19.0
func MySQL8() *Environment
MySQL8 is the collation Environment for MySQL 8. This should only be used for testing where we know it's safe to use this version, and we don't need a specific other version.
func NewEnvironment ¶
func NewEnvironment(serverVersion string) *Environment
NewEnvironment creates a collation Environment for the given MySQL version string. The version string must be in the format that is sent by the server as the version packet when opening a new MySQL connection
func (*Environment) AllCollationIDs ¶ added in v0.18.0
func (env *Environment) AllCollationIDs() []ID
func (*Environment) BinaryCollationForCharset ¶
func (env *Environment) BinaryCollationForCharset(charset string) ID
BinaryCollationForCharset returns the default binary collation for a charset
func (*Environment) CachedSize ¶ added in v0.19.0
func (cached *Environment) CachedSize(alloc bool) int64
func (*Environment) CharsetAlias ¶ added in v0.14.0
func (env *Environment) CharsetAlias(charset string) (alias string, ok bool)
CharsetAlias returns the internal charset name for the given charset. For now, this only maps `utf8` to `utf8mb3`; in future versions of MySQL, this mapping will change, so it's important to use this helper so that Vitess code has a consistent mapping for the active collations environment.
func (*Environment) CollationAlias ¶ added in v0.16.0
func (env *Environment) CollationAlias(collation string) (string, bool)
CollationAlias returns the internal collaction name for the given charset. For now, this maps all `utf8` to `utf8mb3` collation names; in future versions of MySQL, this mapping will change, so it's important to use this helper so that Vitess code has a consistent mapping for the active collations environment.
func (*Environment) DefaultCollationForCharset ¶
func (env *Environment) DefaultCollationForCharset(charset string) ID
DefaultCollationForCharset returns the default collation for a charset
func (*Environment) DefaultConnectionCharset ¶
func (env *Environment) DefaultConnectionCharset() ID
DefaultConnectionCharset is the default charset that Vitess will use when negotiating a charset in a MySQL connection handshake. Note that in this context, a 'charset' is equivalent to a Collation ID, with the exception that it can only fit in 1 byte. For MySQL 8.0+ environments, the default charset is `utf8mb4_0900_ai_ci`. For older MySQL environments, the default charset is `utf8mb4_general_ci`.
func (*Environment) EnsureCollate ¶
func (env *Environment) EnsureCollate(fromID, toID ID) error
func (*Environment) IsSupported ¶ added in v0.18.3
func (env *Environment) IsSupported(coll ID) bool
func (*Environment) LookupByCharset ¶ added in v0.18.0
func (env *Environment) LookupByCharset(name string) *colldefaults
func (*Environment) LookupByName ¶
func (env *Environment) LookupByName(name string) ID
LookupByName returns the collation with the given name.
func (*Environment) LookupCharsetName ¶ added in v0.18.0
func (env *Environment) LookupCharsetName(coll ID) string
func (*Environment) LookupID ¶
func (env *Environment) LookupID(name string) (ID, bool)
LookupID returns the collation ID for the given name, and whether the collation is supported by this package.
func (*Environment) LookupName ¶ added in v0.18.0
func (env *Environment) LookupName(id ID) string
LookupName returns the collation name for the given ID and whether the collation is supported by this package.
func (*Environment) ParseConnectionCharset ¶
func (env *Environment) ParseConnectionCharset(csname string) (ID, error)
ParseConnectionCharset parses the given charset name and returns its numerical identifier to be used in a MySQL connection handshake. The charset name can be: - the name of a character set, in which case the default collation ID for the character set is returned. - the name of a collation, in which case the ID for the collation is returned, UNLESS the collation itself has an ID greater than 255; such collations are not supported because they cannot be negotiated in a single byte in our connection handshake. - empty, in which case the default connection charset for this MySQL version is returned.
type ID ¶
type ID uint16
ID is a numeric identifier for a collation. These identifiers are defined by MySQL, not by Vitess.
const Unknown ID = 0
Unknown is the default ID for an unknown collation.
type Repertoire ¶
type Repertoire byte
Repertoire is a constant that defines the collection of characters in an expression. MySQL only distinguishes between an ASCII repertoire (i.e. an expression where all the contained codepoints are < 128), or an Unicode repertoire (an expression that can contain any possible codepoint).
See: https://dev.mysql.com/doc/refman/8.0/en/charset-repertoire.html
const ( RepertoireASCII Repertoire = iota RepertoireUnicode )
type TypedCollation ¶
type TypedCollation struct { Collation ID Coercibility Coercibility Repertoire Repertoire }
TypedCollation is the Collation of a SQL expression, including its coercibility and repertoire.
func (TypedCollation) Valid ¶
func (tc TypedCollation) Valid() bool
Source Files ¶
Directories ¶
Path | Synopsis |
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korean
Package korean provides Korean encodings such as EUC-KR.
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Package korean provides Korean encodings such as EUC-KR. |
simplifiedchinese
Package simplifiedchinese provides Simplified Chinese encodings such as GBK.
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Package simplifiedchinese provides Simplified Chinese encodings such as GBK. |
internal
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tools
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text is a repository of text-related packages related to internationalization (i18n) and localization (l10n), such as character encodings, text transformations, and locale-specific text handling.
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text is a repository of text-related packages related to internationalization (i18n) and localization (l10n), such as character encodings, text transformations, and locale-specific text handling. |
collate
Package collate contains types for comparing and sorting Unicode strings according to a given collation order.
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Package collate contains types for comparing and sorting Unicode strings according to a given collation order. |
unicode
unicode holds packages with implementations of Unicode standards that are mostly used as building blocks for other packages in vitess.io/vitess/go/mysql/collations/vindex, layout engines, or are otherwise more low-level in nature.
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unicode holds packages with implementations of Unicode standards that are mostly used as building blocks for other packages in vitess.io/vitess/go/mysql/collations/vindex, layout engines, or are otherwise more low-level in nature. |
unicode/norm
Package norm contains types and functions for normalizing Unicode strings.
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Package norm contains types and functions for normalizing Unicode strings. |