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Documentation, firebird.conf

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AlexPeshkoff 2019-11-13 13:50:11 +03:00 committed by Alexander Peshkov
parent 0dce25ffc1
commit be6c4c2d28
2 changed files with 46 additions and 10 deletions
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20
builds/install/misc/firebird.conf.in
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@ -429,8 +429,8 @@
# plugin using SHA-1 for the client proof. This enables backwards compatibility
# with old Firebird 3 servers but does not comply with NIST security requirements.
#
# The default client configuration (AuthClient) also supports the pre-Firebird 3 legacy
# authentication protocol (Legacy_Auth). This is again for backwards
# The default client configuration (AuthClient) also supports the pre-Firebird 3 legacy
# authentication protocol (Legacy_Auth). This is again for backwards
# compatibility but has many known weaknesses and is deprecated for current use.
#
# The default Windows client configuration (AuthClient) also includes support for
@ -657,7 +657,7 @@
# mode by default. In this mode rec_version/no_rec_version transaction flags have
# no effect. Setting this parameter to 0 effectively reverts engine to legacy
# behavior.
#
#
# CAUTION!
# There is no guarantee that legacy behavior will be available in future Firebird
# versions.
@ -666,6 +666,20 @@
#
#ReadConsistency = 1
# ----------------------------
# Engine currently provides a number of new datatypes unknown to legacy clients.
# In order to simplify use of old applications set this parameter to minor FB
# version datatype compatibility with which you need. Currently two values are
# supported: 3.0 & 2.5.
# More precise (including per-session) tuning is possible via SQL and DPB.
#
# Per-database configurable.
#
# Type: string
#
#DataTypeCompatibility =
# ----------------------------
# Client Connection Settings (Basic)
#

36
doc/sql.extensions/README.set_bind.md
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@ -20,23 +20,45 @@ SET BIND OF type NATIVE;
Makes it possible to define rules of describing types of returned to the client columns in non-standard way -
`type-from` is replaced with `type-to`, automatic data coercion takes place.
Except SQL-statement there are two more ways to specify data coercion - tag `isc_dpb_bind` in DPB
and `SetBind` parameter in firebird.conf & databases.conf. The later the rule is introduced (.conf->DPB->SQL)
the higher priotiy it has. I.e. one can override any preconfigured settings from SQL statement.
When incomplete type definition is used (i.e. `CHAR` instead `CHAR(n)`) in left part of `SET BIND` coercion
will take place for all `CHAR` columns, not only default `CHAR(1)`.
When incomplete type definiton is used in right side of the statement (TO part) firebird engine will define missing
details about that type automatically based on source column.
Special `TO` part format `LEGACY` is used when datatype, missing in previous FB version, should be represented in
a way, understandable by old client software (may be with some data losses). For example, `NUMERIC(38)` in legacy
form will be represented as `NUMERIC(18)`.
a way, understandable by old client software (may be with some data losses). The following coercions are done for
legacy datatypes:
| Native datatype | Legacy datatype |
|---|---|
| BOOLEAN | CHAR(5) |
| DECFLOAT | DOUBLE PRECISION |
| NUMERIC(38) | NUMERIC(18) |
| TIME WITH TIME ZONE | TIME WITHOUT TIME ZONE |
| TIMESTAMP WITH TIME ZONE | TIMESTAMP WITHOUT TIME ZONE |
Setting `NATIVE` means `type` will be used as if there were no previous rules for it.
Except SQL-statement there are two more ways to specify data coercion - tag `isc_dpb_bind` in DPB
and `DataTypeCompatibility` parameter in firebird.conf & databases.conf. The later the rule is introduced
(.conf->DPB->SQL) the higher priotiy it has.
I.e. one can override .conf in any other way any DPB from SQL statement.
### Samples:
Value of clumplet with `isc_dpb_bind` tag in DPB should be specified as a set of partially
formed SET BIND statements, i.e. with prefix SET BIND OF is omitted, separated by semicolons.
For example:
```c++
dpb->insertString(&status, isc_dpb_bind, "decfloat to char; numeric(38) to char");
```
`DataTypeCompatibility` is minor firebird version for which we want to provide some compatibility
regarding data types. That compatibility may be not absolute - for example SET BIND can't care about type
of particular SQL functions. The following types will be described in legacy form when `DataTypeCompatibility=3.0:`
DECFLOAT, NUMERIC(38) and TIME(STAMP) WITH TIME ZONE. When `DataTypeCompatibility=2.5` in addition to this
list BOOLEAN will be described as legacy type as well.
### SQL Samples:
```sql
SELECT CAST('123.45' AS DECFLOAT(16)) FROM RDB$DATABASE; --native