Appendix D: System Tables

Appendix D: System Tables

When you create a database, the Firebird engine creates a lot of system tables. Metadata — the descriptions and attributes of all database objects — are stored in these system tables.

System table identifiers all begin with the prefix RDB$.

List of System Tables

RDB$BACKUP_HISTORY

History of backups performed using nBackup

RDB$CHARACTER_SETS

Names and describes the character sets available in the database

RDB$CHECK_CONSTRAINTS

Cross references between the names of constraints (NOT NULL constraints, CHECK constraints and ON UPDATE and ON DELETE clauses in foreign key constraints) and their associated system-generated triggers

RDB$COLLATIONS

Collation sequences for all character sets

RDB$DATABASE

Basic information about the database

RDB$DEPENDENCIES

Information about dependencies between database objects

RDB$EXCEPTIONS

Custom database exceptions

RDB$FIELDS

Column and domain definitions, both system and custom

RDB$FIELD_DIMENSIONS

Dimensions of array columns

RDB$FILES

Information about secondary files and shadow files

RDB$FILTERS

Information about BLOB filters

RDB$FORMATS

Information about changes in the formats of tables

RDB$FUNCTIONS

Information about external functions

RDB$FUNCTION_ARGUMENTS

Attributes of the parameters of external functions

RDB$GENERATORS

Information about generators (sequences)

RDB$INDEX_SEGMENTS

Segments and index positions

RDB$INDICES

Definitions of all indexes in the database (system- or user-defined)

RDB$LOG_FILES

Not used in the current version

RDB$PAGES

Information about database pages

RDB$PROCEDURE_PARAMETERS

Parameters of stored procedures

RDB$PROCEDURES

Definitions of stored procedures

RDB$REF_CONSTRAINTS

Definitions of referential constraints (foreign keys)

RDB$RELATION_CONSTRAINTS

Definitions of all table-level constraints

RDB$RELATION_FIELDS

Top-level definitions of table columns

RDB$RELATIONS

Headers of tables and views

RDB$ROLES

Role definitions

RDB$SECURITY_CLASSES

Access control lists

RDB$TRANSACTIONS

State of multi-database transactions

RDB$TRIGGER_MESSAGES

Trigger messages

RDB$TRIGGERS

Trigger definitions

RDB$TYPES

Definitions of enumerated data types

RDB$USER_PRIVILEGES

SQL privileges granted to system users

RDB$VIEW_RELATIONS

Tables that are referred to in view definitions: one record for each table in a view

`RDB$BACKUP_HISTORY`

RDB$BACKUP_HISTORY stores the history of backups performed using the nBackup utility.

Column Name	Data Type	Description
`RDB$BACKUP_ID`	`INTEGER`	The identifier assigned by the engine
`RDB$TIMESTAMP`	`TIMESTAMP`	Backup date and time
`RDB$BACKUP_LEVEL`	`INTEGER`	Backup level
`RDB$GUID`	`CHAR(38)`	Unique identifier
`RDB$SCN`	`INTEGER`	System (scan) number
`RDB$FILE_NAME`	`VARCHAR(255)`	Full path and file name of backup file

`RDB$CHARACTER_SETS`

RDB$CHARACTER_SETS names and describes the character sets available in the database.

Column Name	Data Type	Description
`RDB$CHARACTER_SET_NAME`	`CHAR(31)`	Character set name
`RDB$FORM_OF_USE`	`CHAR(31)`	Not used
`RDB$NUMBER_OF_CHARACTERS`	`INTEGER`	The number of characters in the set. Not used for existing character sets
`RDB$DEFAULT_COLLATE_NAME`	`CHAR(31)`	The name of the default collation sequence for the character set
`RDB$CHARACTER_SET_ID`	`SMALLINT`	Unique character set identifier
`RDB$SYSTEM_FLAG`	`SMALLINT`	System flag: value is 1 if the character set is defined in the system when the database is created; value is 0 for a user-defined character set
`RDB$DESCRIPTION`	`BLOB TEXT`	Could store text description of the character set
`RDB$FUNCTION_NAME`	`CHAR(31)`	For a user-defined character set that is accessed via an external function, the name of the external function
`RDB$BYTES_PER_CHARACTER`	`SMALLINT`	The maximum number of bytes representing one character

`RDB$CHECK_CONSTRAINTS`

RDB$CHECK_CONSTRAINTS provides the cross references between the names of system-generated triggers for constraints and the names of the associated constraints (NOT NULL constraints, CHECK constraints and the ON UPDATE and ON DELETE clauses in foreign key constraints).

Column Name	Data Type	Description
`RDB$CONSTRAINT_NAME`	`CHAR(31)`	Constraint name, defined by the user or automatically generated by the system
`RDB$TRIGGER_NAME`	`CHAR(31)`	For a `CHECK` constraint, it is the name of the trigger that enforces this constraint. For a `NOT NULL` constraint, it is the name of the table the constraint is applied to. For a foreign key constraint, it is the name of the trigger that enforces the `ON UPDATE`, `ON DELETE` clauses.

`RDB$COLLATIONS`

RDB$COLLATIONS stores collation sequences for all character sets.

Column Name	Data Type	Description
`RDB$COLLATION_NAME`	`CHAR(31)`	Collation sequence name
`RDB$COLLATION_ID`	`SMALLINT`	Collation sequence identifier. Together with the character set identifier, it is a unique collation sequence identifier
`RDB$CHARACTER_SET_ID`	`SMALLINT`	Character set identifier. Together with the collection sequence identifier, it is a unique identifier
`RDB$COLLATION_ATTRIBUTES`	`SMALLINT`	Collation attributes. It is a bit mask where the first bit shows whether trailing spaces should be taken into account in collations (0 - NO PAD; 1 - PAD SPACE); the second bit shows whether the collation is case-sensitive (0 - CASE SENSITIVE, 1 - CASE INSENSITIVE); the third bit shows whether the collation is accent-sensitive (0 - ACCENT SENSITIVE, 1 - ACCENT SENSITIVE). Thus, the value of 5 means that the collation does not take into account trailing spaces and is accent-insensitive
`RDB$SYSTEM_FLAG`	`SMALLINT`	Flag: the value of 0 means it is user-defined; the value of 1 means it is system-defined
`RDB$DESCRIPTION`	`BLOB TEXT`	Could store text description of the collation sequence
`RDB$FUNCTION_NAME`	`CHAR(31)`	Not currently used
`RDB$BASE_COLLATION_NAME`	`CHAR(31)`	The name of the base collation sequence for this collation sequence
`RDB$SPECIFIC_ATTRIBUTES`	`BLOB TEXT`	Describes specific attributes

`RDB$DATABASE`

RDB$DATABASE stores basic information about the database. It contains only one record.

Column Name	Data Type	Description
`RDB$DESCRIPTION`	`BLOB TEXT`	Database comment text
`RDB$RELATION_ID`	`SMALLINT`	A number that steps up by one each time a table or view is added to the database
`RDB$SECURITY_CLASS`	`CHAR(31)`	The security class defined in `RDB$SECURITY_CLASSES` in order to apply access control limits common to the entire database
`RDB$CHARACTER_SET_NAME`	`CHAR(31)`	The name of the default character set for the database set in the `DEFAULT CHARACTER SET` clause when the database is created. `NULL` for character set `NONE`.

`RDB$DEPENDENCIES`

RDB$DEPENDENCIES stores the dependencies between database objects.

Column Name	Data Type	Description
`RDB$DEPENDENT_NAME`	`CHAR(31)`	The name of the view, procedure, trigger, `CHECK` constraint or computed column the dependency is defined for, i.e., the dependent object
`RDB$DEPENDED_ON_NAME`	`CHAR(31)`	The name of the object that the defined object — the table, view, procedure, trigger, `CHECK` constraint or computed column — depends on
`RDB$FIELD_NAME`	`CHAR(31)`	The column name in the depended-on object that is referred to by the dependent view, procedure, trigger, `CHECK` constraint or computed column
`RDB$DEPENDENT_TYPE`	`SMALLINT`	Identifies the type of the dependent object: `0` - table `1` - view `2` - trigger `3` - computed column `4` - `CHECK` constraint `5` - procedure `6` - index expression `7` - exception `8` - user `9` - column `10` - index
`RDB$DEPENDED_ON_TYPE`	`SMALLINT`	Identifies the type of the object depended on: `0` - table (or a column in it) `1` - view `2` - trigger `3` - computed column `4` - `CHECK` constraint `5` - procedure (or its parameter[s]) `6` - index expression `7` - exception `8` - user `9` - column `10` - index `14` - generator (sequence) `15` - UDF `17` - collation

`RDB$EXCEPTIONS`

RDB$EXCEPTIONS stores custom database exceptions.

Column Name	Data Type	Description
`RDB$EXCEPTION_NAME`	`CHAR(31)`	Custom exception name
`RDB$EXCEPTION_NUMBER`	`INTEGER`	The unique number of the exception assigned by the system
`RDB$MESSAGE`	`VARCHAR(1021)`	Exception message text
`RDB$DESCRIPTION`	`BLOB TEXT`	Could store text description of the exception
`RDB$SYSTEM_FLAG`	`SMALLINT`	Flag: `0` - user-defined `1` or higher - system-defined

`RDB$FIELDS`

RDB$FIELDS stores definitions of columns and domains, both system and custom. This is where the detailed data attributes are stored for all columns.

The column RDB$FIELDS.RDB$FIELD_NAME links to RDB$RELATION_FIELDS.RDB$FIELD_SOURCE, not to RDB$RELATION_FIELDS.RDB$FIELD_NAME.

Column Name	Data Type	Description
`RDB$FIELD_NAME`	`CHAR(31)`	The unique name of the domain created by the user or of the domain automatically built for the table column by the system. System-created domain names start with the “RDB$” prefix
`RDB$QUERY_NAME`	`CHAR(31)`	Not used
`RDB$VALIDATION_BLR`	`BLOB BLR`	The binary language representation (BLR) of the SQL expression specifying the check of the `CHECK` value in the domain
`RDB$VALIDATION_SOURCE`	`BLOB TEXT`	The original source text in the SQL language specifying the check of the `CHECK` value
`RDB$COMPUTED_BLR`	`BLOB BLR`	The binary language representation (BLR) of the SQL expression the database server uses for evaluation when accessing a `COMPUTED BY` column
`RDB$COMPUTED_SOURCE`	`BLOB TEXT`	The original source text of the expression that defines a `COMPUTED BY` column
`RDB$DEFAULT_VALUE`	`BLOB BLR`	The default value, if any, for the field or domain, in binary language representation (BLR)
`RDB$DEFAULT_SOURCE`	`BLOB TEXT`	The default value in the source code, as an SQL constant or expression
`RDB$FIELD_LENGTH`	`SMALLINT`	Column size in bytes. `FLOAT`, `DATE`, `TIME`, `INTEGER` occupy 4 bytes. `DOUBLE PRECISION`, `BIGINT`, `TIMESTAMP` and `BLOB` identifier occupy 8 bytes. For the `CHAR` and `VARCHAR` data types, the column stores the maximum number of bytes specified when a string domain (column) is defined
`RDB$FIELD_SCALE`	`SMALLINT`	The negative number that specifies the scale for `DECIMAL` and `NUMERIC` columns — the number of digits after the decimal point
`RDB$FIELD_TYPE`	`SMALLINT`	Data type code for the column: `7` - `SMALLINT 8</code> - <code>INTEGER<br>10` - `FLOAT` `12` - `DATE` `13` - `TIME` `14` - `CHAR` `16` - `BIGINT` `27` - `DOUBLE PRECISION` `35` - `TIMESTAMP` `37` - `VARCHAR` `261` - `BLOB` Codes for `DECIMAL` and `NUMERIC` are the same as for the integer types used to store them
`RDB$FIELD_SUB_TYPE`	`SMALLINT`	Specifies the subtype for the BLOB data type: `0` - untyped `1` - text `2` - BLR `3` - access control list `4` - reserved for future use `5` - encoded table metadata description `6` - for storing the details of a cross-database transaction that ends abnormally Specifies for the CHAR data type: `0` - untyped data `1` - fixed binary data Specifies the particular data type for the integer data types (`SMALLINT`, `INTEGER`, `BIGINT`) and for fixed-point numbers (`NUMERIC`, `DECIMAL`): `0` or `NULL` - the data type matches the value in the `RDB$FIELD_TYPE` field `1` - `NUMERIC` `2` - `DECIMAL`
`RDB$MISSING_VALUE`	`BLOB BLR`	Not used
`RDB$MISSING_SOURCE`	`BLOB TEXT`	Not used
`RDB$DESCRIPTION`	`BLOB TEXT`	Any domain (table column) comment text
`RDB$SYSTEM_FLAG`	`SMALLINT`	Flag: the value of 1 means the domain is automatically created by the system, the value of 0 means that the domain is defined by the user
`RDB$QUERY_HEADER`	`BLOB TEXT`	Not used
`RDB$SEGMENT_LENGTH`	`SMALLINT`	Specifies the length of the `BLOB` buffer in bytes for `BLOB` columns. Stores `NULL` for all other data types
`RDB$EDIT_STRING`	`VARCHAR(127)`	Not used
`RDB$EXTERNAL_LENGTH`	`SMALLINT`	The length of the column in bytes if it belongs to an external table. Always `NULL` for regular tables
`RDB$EXTERNAL_SCALE`	`SMALLINT`	The scale factor of an integer-type field in an external table; represents the power of 10 by which the integer is multiplied
`RDB$EXTERNAL_TYPE`	`SMALLINT`	The data type of the field as it is represented in an external table: `7` - `SMALLINT` `8` - `INTEGER` `10` - `FLOAT` `12` - `DATE` `13` - `TIME` `14` - `CHAR` `16` - `BIGINT` `27` - `DOUBLE PRECISION` `35` - `TIMESTAMP` `37` - `VARCHAR` `261` - `BLOB`
`RDB$DIMENSIONS`	`SMALLINT`	Defines the number of dimensions in an array if the column is defined as an array. Always `NULL` for columns that are not arrays
`RDB$NULL_FLAG`	`SMALLINT`	Specifies whether the column can take an empty value (the field will contain `NULL`) or not (the field will contain the value of 1)
`RDB$CHARACTER_LENGTH`	`SMALLINT`	The length of `CHAR` or `VARCHAR` columns in characters (not in bytes)
`RDB$COLLATION_ID`	`SMALLINT`	The identifier of the collation sequence for a character column or domain. If it is not defined, the value of the field will be 0
`RDB$CHARACTER_SET_ID`	`SMALLINT`	The identifier of the character set for a character column, `BLOB TEXT` column or domain
`RDB$FIELD_PRECISION`	`SMALLINT`	Specifies the total number of digits for the fixed-point numeric data type (`DECIMAL` and `NUMERIC`). The value is 0 for the integer data types, `NULL` is for other data types

`RDB$FIELD_DIMENSIONS`

RDB$FIELD_DIMENSIONS stores the dimensions of array columns.

Column Name	Data Type	Description
`RDB$FIELD_NAME`	`CHAR(31)`	The name of the array column. It must be present in the `RDB$FIELD_NAME` field of the `RDB$FIELDS` table
`RDB$DIMENSION`	`SMALLINT`	Identifies one dimension in the array column. The numbering of dimensions starts with 0
`RDB$LOWER_BOUND`	`INTEGER`	The lower bound of this dimension
`RDB$UPPER_BOUND`	`INTEGER`	The upper bound of this dimension

`RDB$FILES`

RDB$FILES stores information about secondary files and shadow files.

Column Name	Data Type	Description
`RDB$FILE_NAME`	`VARCHAR(255)`	The full path to the file and the name of either the database secondary file in a multi-file database, or the shadow file
`RDB$FILE_SEQUENCE`	`SMALLINT`	The sequential number of the secondary file in a sequence or of the shadow file in a shadow file set
`RDB$FILE_START`	`INTEGER`	The initial page number in the secondary file or shadow file
`RDB$FILE_LENGTH`	`INTEGER`	File length in database pages
`RDB$FILE_FLAGS`	`SMALLINT`	For internal use
`RDB$SHADOW_NUMBER`	`SMALLINT`	Shadow set number. If the row describes a database secondary file, the field will be `NULL` or its value will be 0

`RDB$FILTERS`

RDB$FILTERS stores information about BLOB filters.

Column Name	Data Type	Description
`RDB$FUNCTION_NAME`	`CHAR(31)`	The unique identifier of the `BLOB` filter
`RDB$DESCRIPTION`	`BLOB TEXT`	Documentation about the `BLOB` filter and the two subtypes it is used with, written by the user
`RDB$MODULE_NAME`	`VARCHAR(255)`	The name of the dynamic library or shared object where the code of the `BLOB` filter is located
`RDB$ENTRYPOINT`	`CHAR(31)`	The exported name of the `BLOB` filter in the filter library. Note, this is often not the same as `RDB$FUNCTION_NAME`, which is the identifier with which the `BLOB` filter is declared to the database
`RDB$INPUT_SUB_TYPE`	`SMALLINT`	The `BLOB` subtype of the data to be converted by the function
`RDB$OUTPUT_SUB_TYPE`	`SMALLINT`	The `BLOB` subtype of the converted data
`RDB$SYSTEM_FLAG`	`SMALLINT`	Flag indicating whether the filter is user-defined or internally defined: `0` - user-defined `1` or greater - internally defined

`RDB$FORMATS`

RDB$FORMATS stores information about changes in tables. Each time any metadata change to a table is committed, it gets a new format number. When the format number of any table reaches 255, the entire database becomes inoperable. To return to normal, the database must be backed up with the gbak utility and restored from that backup copy.

Column Name	Data Type	Description
`RDB$RELATION_ID`	`SMALLINT`	Table or view identifier
`RDB$FORMAT`	`SMALLINT`	Table format identifier — maximum 255. The critical time comes when this number approaches 255 for any table or view
`RDB$DESCRIPTOR`	`BLOB FORMAT`	Stores column names and data attributes as `BLOB`, as they were at the time the format record was created

`RDB$FUNCTIONS`

RDB$FUNCTIONS stores the information needed by the engine about external functions (user-defined functions, UDFs).

In future major releases (Firebird 3.0+) RDB$FUNCTIONS will also store the information about stored functions: user-defined functions written in PSQL.

Column Name	Data Type	Description
`RDB$FUNCTION_NAME`	`CHAR(31)`	The unique (declared) name of the external function
`RDB$FUNCTION_TYPE`	`SMALLINT`	Not currently used
`RDB$QUERY_NAME`	`CHAR(31)`	Not currently used
`RDB$DESCRIPTION`	`BLOB TEXT`	Any text with comments related to the external function
`RDB$MODULE_NAME`	`VARCHAR(255)`	The name of the dynamic library or shared object where the code of the external function is located
`RDB$ENTRYPOINT`	`CHAR(31)`	The exported name of the external function in the function library. Note, this is often not the same as `RDB$FUNCTION_NAME`, which is the identifier with which the external function is declared to the database
`RDB$RETURN_ARGUMENT`	`SMALLINT`	The position number of the returned argument in the list of parameters corresponding to input arguments
`RDB$SYSTEM_FLAG`	`SMALLINT`	Flag indicating whether the filter is user-defined or internally defined: `0` - user-defined `1` - internally defined

`RDB$FUNCTION_ARGUMENTS`

RDB$FUNCTION_ARGUMENTS stores the parameters of external functions and their attributes.

Column Name	Data Type	Description
`RDB$FUNCTION_NAME`	`CHAR(31)`	The unique name (declared identifier) of the external function
`RDB$ARGUMENT_POSITION`	`SMALLINT`	The position of the argument in the list of arguments
`RDB$MECHANISM`	`SMALLINT`	Flag: how this argument is passed: `0` - by value `1` - by reference `2` - by descriptor `3` - by BLOB descriptor
`RDB$FIELD_TYPE`	`SMALLINT`	Data type code defined for the column: `7` - `SMALLINT` `8` - `INTEGER` `12` - `DATE` `13` - `TIME` `14` - `CHAR` `16` - `BIGINT` `27` - `DOUBLE PRECISION` `35` - `TIMESTAMP` `37` - `VARCHAR` `40` - `CSTRING` (null-terminated text) `45` - `BLOB_ID` `261` - `BLOB`
`RDB$FIELD_SCALE`	`SMALLINT`	The scale of an integer or a fixed-point argument. It is an exponent of 10
`RDB$FIELD_LENGTH`	`SMALLINT`	Argument length in bytes: `SMALLINT` = 2 `INTEGER` = 4 `DATE` = 4 `TIME` = 4 `BIGINT` = 8 `DOUBLE PRECISION` = 8 `TIMESTAMP` = 8 `BLOB_ID` = 8
`RDB$FIELD_SUB_TYPE`	`SMALLINT`	Stores the `BLOB` subtype for an argument of a `BLOB` data type
`RDB$CHARACTER_SET_ID`	`SMALLINT`	The identifier of the character set for a character argument
`RDB$FIELD_PRECISION`	`SMALLINT`	The number of digits of precision available for the data type of the argument
`RDB$CHARACTER_LENGTH`	`SMALLINT`	The length of a `CHAR` or `VARCHAR` argument in characters (not in bytes)

`RDB$GENERATORS`

RDB$GENERATORS stores generators (sequences) and keeps them up-to-date.

Column Name	Data Type	Description
`RDB$GENERATOR_NAME`	`CHAR(31)`	The unique name of the generator
`RDB$GENERATOR_ID`	`SMALLINT`	The unique identifier assigned to the generator by the system
`RDB$SYSTEM_FLAG`	`SMALLINT`	Flag: `0` - user-defined `1` or greater - system-defined
`RDB$DESCRIPTION`	`BLOB TEXT`	Could store comments related to the generator

`RDB$INDICES`

RDB$INDICES stores definitions of both system- and user-defined indexes. The attributes of each column belonging to an index are stored in one row of the table RDB$INDEX_SEGMENTS.

Column Name	Data Type	Description
`RDB$INDEX_NAME`	`CHAR(31)`	The unique name of the index specified by the user or automatically generated by the system
`RDB$RELATION_NAME`	`CHAR(31)`	The name of the table to which the index belongs. It corresponds to an identifier in `RDB$RELATION_NAME.RDB$RELATIONS`
`RDB$INDEX_ID`	`SMALLINT`	The internal (system) identifier of the index
`RDB$UNIQUE_FLAG`	`SMALLINT`	Specifies whether the index is unique: `0` - not unique `1` - unique
`RDB$DESCRIPTION`	`BLOB TEXT`	Could store comments concerning the index
`RDB$SEGMENT_COUNT`	`SMALLINT`	The number of segments (columns) in the index
`RDB$INDEX_INACTIVE`	`SMALLINT`	Indicates whether the index is currently active: `0` - active `1` - inactive
`RDB$INDEX_TYPE`	`SMALLINT`	Distinguishes between an expression index (1) and a regular index (0 or null). Not used in databases created before Firebird 2.0; hence, regular indexes in upgraded databases are more more likely to store null in this column
`RDB$FOREIGN_KEY`	`CHAR(31)`	The name of the associated Foreign Key constraint, if any
`RDB$SYSTEM_FLAG`	`SMALLINT`	Indicates whether the index is system-defined or user-defined: `0` - user-defined `1` or greater - system-defined
`RDB$EXPRESSION_BLR`	`BLOB BLR`	Expression for an expression index, written in the binary language representation (BLR), used for calculating the values for the index at runtime.
`RDB$EXPRESSION_SOURCE`	`BLOB TEXT`	The source code of the expression for an expression index
`RDB$STATISTICS`	`DOUBLE PRECISION`	Stores the last known selectivity of the entire index, calculated by execution of a `SET STATISTICS` statement over the index. It is also recalculated whenever the database is first opened by the server. The selectivity of each separate segment of the index is stored in `RDB$INDEX_SEGMENTS`.

`RDB$INDEX_SEGMENTS`

RDB$INDEX_SEGMENTS stores the segments (table columns) of indexes and their positions in the key. A separate row is stored for each column in an index.

Column Name	Data Type	Description
`RDB$INDEX_NAME`	`CHAR(31)`	The name of the index this segment is related to. The master record is `RDB$INDICES.RDB$INDEX_NAME`.
`RDB$FIELD_NAME`	`CHAR(31)`	The name of a column belonging to the index, corresponding to an identifier for the table and that column in `RDB$RELATION_FIELDS.RDB$FIELD_NAME`
`RDB$FIELD_POSITION`	`SMALLINT`	The column position in the index. Positions are numbered left-to-right, starting at zero
`RDB$STATISTICS`	`DOUBLE PRECISION`	The last known (calculated) selectivity of this column in the index. The higher the number, the lower the selectivity.

`RDB$LOG_FILES`

RDB$LOG_FILES is not currently used.

`RDB$PAGES`

RDB$PAGES stores and maintains information about database pages and their usage.

Column Name	Data Type	Description
`RDB$PAGE_NUMBER`	`INTEGER`	The unique number of a physically created database page
`RDB$RELATION_ID`	`SMALLINT`	The identifier of the table to which the page is allocated
`RDB$PAGE_SEQUENCE`	`INTEGER`	The number of the page in the sequence of all pages allocated to this table
`RDB$PAGE_TYPE`	`SMALLINT`	Indicates the page type (data, index, `BLOB`, etc.). For system use

`RDB$PROCEDURES`

RDB$PROCEDURES stores the definitions of stored procedures, including their PSQL source code and the binary language representation (BLR) of it. The next table, RDB$PROCEDURE_PARAMETERS, stores the definitions of input and output parameters.

Column Name	Data Type	Description
`RDB$PROCEDURE_NAME`	`CHAR(31)`	Stored procedure name (identifier)
`RDB$PROCEDURE_ID`	`SMALLINT`	The procedure’s unique, system-generated identifier
`RDB$PROCEDURE_INPUTS`	`SMALLINT`	Indicates the number of input parameters. `NULL` if there are none
`RDB$PROCEDURE_OUTPUTS`	`SMALLINT`	Indicates the number of output parameters. `NULL` if there are none
`RDB$DESCRIPTION`	`BLOB TEXT`	Any text comments related to the procedure
`RDB$PROCEDURE_SOURCE`	`BLOB TEXT`	The PSQL source code of the procedure
`RDB$PROCEDURE_BLR`	`BLOB BLR`	The binary language representation (BLR) of the procedure code
`RDB$SECURITY_CLASS`	`CHAR(31)`	May point to the security class defined in the system table `RDB$SECURITY_CLASSES` in order to apply access control limits
`RDB$OWNER_NAME`	`CHAR(31)`	The user name of the procedure’s Owner — the user who was `CURRENT_USER` when the procedure was first created. It may or may not be the user name of the author
`RDB$RUNTIME`	`BLOB`	A metadata description of the procedure, used internally for optimization
`RDB$SYSTEM_FLAG`	`SMALLINT`	Indicates whether the procedure is defined by a user (value 0) or by the system (a value of 1 or greater)
`RDB$PROCEDURE_TYPE`	`SMALLINT`	Procedure type: `1` - selectable stored procedure (contains a SUSPEND statement) `2` - executable stored procedure `NULL` - not known for procedures created before Firebird 1.5
`RDB$VALID_BLR`	`SMALLINT`	Indicates whether the source PSQL of the stored procedure remains valid after the latest `ALTER PROCEDURE` modification
`RDB$DEBUG_INFO`	`BLOB`	Contains debugging information about variables used in the stored procedure

`RDB$PROCEDURE_PARAMETERS`

RDB$PROCEDURE_PARAMETERS stores the parameters of stored procedures and their attributes. It holds one row for each parameter.

Column Name	Data Type	Description
`RDB$PARAMETER_NAME`	`CHAR(31)`	Parameter name
`RDB$PROCEDURE_NAME`	`CHAR(31)`	The name of the procedure where the parameter is defined
`RDB$PARAMETER_NUMBER`	`SMALLINT`	The sequential number of the parameter
`RDB$PARAMETER_TYPE`	`SMALLINT`	Indicates whether the parameter is for input (value 0) or output (value 1)
`RDB$FIELD_SOURCE`	`CHAR(31)`	The name of the user-created domain, when a domain is referenced instead of a data type. If the name starts with the prefix “RDB$”, it is the name of the domain automatically generated by the system for the parameter.
`RDB$DESCRIPTION`	`BLOB TEXT`	Could store comments related to the parameter
`RDB$SYSTEM_FLAG`	`SMALLINT`	Indicates whether the parameter was defined by the system (value or greater) or by a user (value 0)
`RDB$DEFAULT_VALUE`	`BLOB BLR`	The default value for the parameter, in the binary language representation (BLR)
`RDB$DEFAULT_SOURCE`	`BLOB TEXT`	The default value for the parameter, in PSQL code
`RDB$COLLATION_ID`	`SMALLINT`	The identifier of the collation sequence used for a character parameter
`RDB$NULL_FLAG`	`SMALLINT`	The flag indicating whether `NULL` is allowable
`RDB$PARAMETER_MECHANISM`	`SMALLINT`	Flag: indicates how this parameter is passed: `0` - by value `1` - by reference `2` - by descriptor `3` - by BLOB descriptor
`RDB$FIELD_NAME`	`CHAR(31)`	The name of the column the parameter references, if it was declared using `TYPE OF COLUMN` instead of a regular data type. Used in conjunction with `RDB$RELATION_NAME` (see next).
`RDB$RELATION_NAME`	`CHAR(31)`	The name of the table the parameter references, if it was declared using `TYPE OF COLUMN` instead of a regular data type

`RDB$REF_CONSTRAINTS`

RDB$REF_CONSTRAINTS stores the attributes of the referential constraints — Foreign Key relationships and referential actions.

Column Name	Data Type	Description
`RDB$CONSTRAINT_NAME`	`CHAR(31)`	Foreign key constraint name, defined by the user or automatically generated by the system
`RDB$CONST_NAME_UQ`	`CHAR(31)`	The name of the primary or unique key constraint linked by the `REFERENCES` clause in the constraint definition
`RDB$MATCH_OPTION`	`CHAR(7)`	Not used. The current value is `FULL` in all cases
`RDB$UPDATE_RULE`	`CHAR(11)`	Referential integrity actions applied to the foreign key record[s] when the primary (unique) key of the parent table is updated: `RESTRICT`, `NO ACTION`, `CASCADE`, `SET NULL`, `SET DEFAULT`
`RDB$DELETE_RULE`	`CHAR(11)`	Referential integrity actions applied to the foreign key record[s] when the primary (unique) key of the parent table is deleted: `RESTRICT`, `NO ACTION`, `CASCADE`, `SET NULL`, `SET DEFAULT`

`RDB$RELATIONS`

RDB$RELATIONS stores the top-level definitions and attributes of all tables and views in the system.

Column Name	Data Type	Description
`RDB$VIEW_BLR`	`BLOB BLR`	Stores the query specification for a view, in the binary language representation (BLR). The field stores `NULL` for a table
`RDB$VIEW_SOURCE`	`BLOB TEXT`	Contains the original source text of the query for a view, in SQL language. User comments are included. The field stores `NULL` for a table
`RDB$DESCRIPTION`	`BLOB TEXT`	Could store comments related to the table or view
`RDB$RELATION_ID`	`SMALLINT`	Internal identifier of the table or view
`RDB$SYSTEM_FLAG`	`SMALLINT`	indicates whether the table or view is user-defined (value 0) or system-defined (value 1 or greater)
`RDB$DBKEY_LENGTH`	`SMALLINT`	The total length of the database key. For a table: 8 bytes. For a view, the length is 8 multiplied by the number of tables referenced by the view
`RDB$FORMAT`	`SMALLINT`	Internal use, points to the relation’s record in `RDB$FORMATS` — do not modify
`RDB$FIELD_ID`	`SMALLINT`	The field ID for the next column to be added. The number is not decremented when a column is dropped.
`RDB$RELATION_NAME`	`CHAR(31)`	Table or view name
`RDB$SECURITY_CLASS`	`CHAR(31)`	May reference a security class defined in the table `RDB$SECURITY_CLASSES`, in order to apply access control limits to all users of this table or view
`RDB$EXTERNAL_FILE`	`VARCHAR(255)`	The full path to the external data file if the table is defined with the `EXTERNAL FILE` clause
`RDB$RUNTIME`	`BLOB`	Table metadata description, used internally for optimization
`RDB$EXTERNAL_DESCRIPTION`	`BLOB`	Could store comments related to the external file of an external table
`RDB$OWNER_NAME`	`CHAR(31)`	The user name of the user who created the table or view originally
`RDB$DEFAULT_CLASS`	`CHAR(31)`	Default security class, used when a new column is added to the table
`RDB$FLAGS`	`SMALLINT`	Internal flags
`RDB$RELATION_TYPE`	`SMALLINT`	The type of the relation object being described: `0` - system or user-defined table `1` - view `2` - external table `3` - monitoring table `4` - connection-level GTT (`PRESERVE ROWS`) `5` - transaction-level GTT (`DELETE ROWS`)

`RDB$RELATION_CONSTRAINTS`

RDB$RELATION_CONSTRAINTS stores the definitions of all table-level constraints: primary, unique, foreign key, CHECK, NOT NULL constraints.

Column Name	Data Type	Description
`RDB$CONSTRAINT_NAME`	`CHAR(31)`	The name of the table-level constraint defined by the user, or otherwise automatically generated by the system
`RDB$CONSTRAINT_TYPE`	`CHAR(11)`	The name of the constraint type: `PRIMARY KEY`, `UNIQUE`, `FOREIGN KEY`, `CHECK` or `NOT NULL`
`RDB$RELATION_NAME`	`CHAR(31)`	The name of the table this constraint applies to
`RDB$DEFERRABLE`	`CHAR(3)`	Currently `NO` in all cases: Firebird does not yet support deferrable constraints
`RDB$INITIALLY_DEFERRED`	`CHAR(3)`	Currently `NO` in all cases
`RDB$INDEX_NAME`	`CHAR(31)`	The name of the index that supports this constraint. For a `CHECK` or a `NOT NULL` constraint, it is `NULL`.

`RDB$RELATION_FIELDS`

RDB$RELATION_FIELDS stores the definitions of table and view columns.

Column Name	Data Type	Description
`RDB$FIELD_NAME`	`CHAR(31)`	Column name
`RDB$RELATION_NAME`	`CHAR(31)`	The name of the table or view that the column belongs to
`RDB$FIELD_SOURCE`	`CHAR(31)`	Domain name on which the column is based, either a user-defined one specified in the table definition or one created automatically by the system using the set of attributes defined. The attributes are in the table `RDB$FIELDS`: this column matches `RDB$FIELDS.RDB$FIELD_NAME`.
`RDB$QUERY_NAME`	`CHAR(31)`	Not currently used
`RDB$BASE_FIELD`	`CHAR(31)`	Only populated for a view, it is the name of the column from the base table
`RDB$EDIT_STRING`	`VARCHAR(127)`	Not used
`RDB$FIELD_POSITION`	`SMALLINT`	The zero-based ordinal position of the column in the table or view, numbering from left to right
`RDB$QUERY_HEADER`	`BLOB TEXT`	Not used
`RDB$UPDATE_FLAG`	`SMALLINT`	Indicates whether the column is a regular one (value 1) or a computed one (value 0)
`RDB$FIELD_ID`	`SMALLINT`	An ID assigned from `RDB$RELATIONS.RDB$FIELD_ID` at the time the column was added to the table or view. It should always be treated as transient
`RDB$VIEW_CONTEXT`	`SMALLINT`	For a view column, the internal identifier of the base table from which this field derives
`RDB$DESCRIPTION`	`BLOB TEXT`	Comments related to the table or view column
`RDB$DEFAULT_VALUE`	`BLOB BLR`	The value stored for the DEFAULT clause for this column, if there is one, written in binary language representation (BLR)
`RDB$SYSTEM_FLAG`	`SMALLINT`	Indicates whether the column is user-defined (value 0) or system-defined (value 1 or greater)
`RDB$SECURITY_CLASS`	`CHAR(31)`	May reference a security class defined in `RDB$SECURITY_CLASSES`, in order to apply access control limits to all users of this column
`RDB$COMPLEX_NAME`	`CHAR(31)`	Not used
`RDB$NULL_FLAG`	`SMALLINT`	Indicates whether the column is nullable (`NULL`) non-nullable (value 1)
`RDB$DEFAULT_SOURCE`	`BLOB TEXT`	The source text of the `DEFAULT` clause, if any
`RDB$COLLATION_ID`	`SMALLINT`	The identifier of the collation sequence in the character set for the column, if it is not the default collation

`RDB$ROLES`

RDB$ROLES stores the roles that have been defined in this database.

Column Name	Data Type	Description
`RDB$ROLE_NAME`	`CHAR(31)`	Role name
`RDB$OWNER_NAME`	`CHAR(31)`	The user name of the role owner
`RDB$DESCRIPTION`	`BLOB TEXT`	Could store comments related to the role
`RDB$SYSTEM_FLAG`	`SMALLINT`	System flag

`RDB$SECURITY_CLASSES`

RDB$SECURITY_CLASSES stores the access control lists

Column Name	Data Type	Description
`RDB$SECURITY_CLASS`	`CHAR(31)`	Security class name
`RDB$ACL`	`BLOB ACL`	The access control list related to the security class. It enumerates users and their privileges
`RDB$DESCRIPTION`	`BLOB TEXT`	Could store comments related to the security class

`RDB$TRANSACTIONS`

RDB$TRANSACTIONS stores the states of distributed transactions and other transactions that were prepared for two-phase commit with an explicit prepare message.

Column Name	Data Type	Description
`RDB$TRANSACTION_ID`	`INTEGER`	The unique identifier of the transaction being tracked
`RDB$TRANSACTION_STATE`	`SMALLINT`	Transaction state: `0` - in limbo `1` - committed `2` - rolled back
`RDB$TIMESTAMP`	`TIMESTAMP`	Not used
`RDB$TRANSACTION_DESCRIPTION`	`BLOB`	Describes the prepared transaction and could be a custom message supplied to `isc_prepare_transaction2`, even if it is not a distributed transaction. It may be used when a lost connection cannot be restored

`RDB$TRIGGERS`

RDB$TRIGGERS stores the trigger definitions for all tables and views.

Column Name	Data Type	Description
`RDB$TRIGGER_NAME`	`CHAR(31)`	Trigger name
`RDB$RELATION_NAME`	`CHAR(31)`	The name of the table or view the trigger applies to. NULL if the trigger is applicable to a database event (“database trigger”)
`RDB$TRIGGER_SEQUENCE`	`SMALLINT`	Position of this trigger in the sequence. Zero usually means that no sequence position is specified
`RDB$TRIGGER_TYPE`	`SMALLINT`	The event the trigger fires on: `1` - before insert `2` - after insert `3` - before update `4` - after update `5` - before delete `6` - after delete `17` - before insert or update `18` - after insert or update `25` - before insert or delete `26` - after insert or delete `27` - before update or delete `28` - after update or delete `113` - before insert or update or delete `114` - after insert or update or delete `8192` - on connect `8193` - on disconnect `8194` - on transaction start `8195` - on transaction commit `8196` - on transaction rollback
Identification of the exact `RDB$TRIGGER_TYPE` code is a little more complicated, since it is a bitmap, calculated according to which phase and events are covered and the order in which they are defined. For the curious, the calculation is explained in this code comment by Mark Rotteveel.
`RDB$TRIGGER_SOURCE`	`BLOB TEXT`	Stores the source code of the trigger in PSQL
`RDB$TRIGGER_BLR`	`BLOB BLR`	Stores the trigger in the binary language representation (BLR)
`RDB$DESCRIPTION`	`BLOB TEXT`	Trigger comment text
`RDB$TRIGGER_INACTIVE`	`SMALLINT`	Indicates whether the trigger is currently inactive (1) or active (0)
`RDB$SYSTEM_FLAG`	`SMALLINT`	Flag: indicates whether the trigger is user-defined (value 0) or system-defined (value 1 or greater)
`RDB$FLAGS`	`SMALLINT`	Internal use
`RDB$VALID_BLR`	`SMALLINT`	Indicates whether the text of the trigger remains valid after the latest modification by the the `ALTER TRIGGER` statement
`RDB$DEBUG_INFO`	`BLOB`	Contains debugging information about variables used in the trigger

`RDB$TRIGGER_MESSAGES`

RDB$TRIGGER_MESSAGES stores the trigger messages.

Column Name	Data Type	Description
`RDB$TRIGGER_NAME`	`CHAR(31)`	The name of the trigger the message is associated with
`RDB$MESSAGE_NUMBER`	`SMALLINT`	The number of the message within this trigger (from 1 to 32,767)
`RDB$MESSAGE`	`VARCHAR(1023)`	Text of the trigger message

`RDB$TYPES`

RDB$TYPES stores the defining sets of enumerated types used throughout the system.

Column Name	Data Type	Description
`RDB$FIELD_NAME`	`CHAR(31)`	Enumerated type name. Each type name masters its own set of types, e.g., object types, data types, character sets, trigger types, blob subtypes, etc.
`RDB$TYPE`	`SMALLINT`	The object type identifier. A unique series of numbers is used within each separate enumerated type. For example, in this selection from the set mastered under `RDB$OBJECT_TYPE` in `RDB$FIELD_NAME`, some object types are enumerated: `0` - TABLE `1` - VIEW `2` - TRIGGER `3` - COMPUTED_FIELD `4` - VALIDATION `5` - PROCEDURE …
`RDB$TYPE_NAME`	`CHAR(31)`	The name of a member of an enumerated type, e.g., TABLE, VIEW, TRIGGER, etc. in the example above. In the `RDB$CHARACTER_SET` enumerated type, `RDB$TYPE_NAME` stores the names of the character sets.
`RDB$DESCRIPTION`	`BLOB TEXT`	Any text comments related to the enumerated type
`RDB$SYSTEM_FLAG`	`SMALLINT`	Flag: indicates whether the type-member is user-defined (value 0) or system-defined (value 1 or greater)

`RDB$USER_PRIVILEGES`

RDB$USER_PRIVILEGES stores the SQL access privileges for Firebird users and privileged objects.

Column Name	Data Type	Description
`RDB$USER`	`CHAR(31)`	The user or object that is granted this privilege
`RDB$GRANTOR`	`CHAR(31)`	The user who grants the privilege
`RDB$PRIVILEGE`	`CHAR(6)`	The privilege granted hereby: `A` - all (all privileges) `S` - select (selecting data) `I` - insert (inserting rows) `D` - delete (deleting rows) `R` - references (foreign key) `U` - update (updating data) `X` - executing (procedure)
`RDB$GRANT_OPTION`	`SMALLINT`	Whether the WITH GRANT OPTION authority is included with the privilege: `0` - not included `1` - included
`RDB$RELATION_NAME`	`CHAR(31)`	The name of the object (table, view, procedure or role) the privilege is granted ON
`RDB$FIELD_NAME`	`CHAR(31)`	The name of the column the privilege is applicable to, for a column-level privilege (an `UPDATE` or `REFERENCES` privilege)
`RDB$USER_TYPE`	`SMALLINT`	Identifies the type of user the privilege is granted TO (a user, a procedure, a view, etc.)
`RDB$OBJECT_TYPE`	`SMALLINT`	Identifies the type of the object the privilege is granted ON

`RDB$VIEW_RELATIONS`

RDB$VIEW_RELATIONS stores the tables that are referred to in view definitions. There is one record for each table in a view.

Column Name	Data Type	Description
`RDB$VIEW_NAME`	`CHAR(31)`	View name
`RDB$RELATION_NAME`	`CHAR(31)`	The name of the table the view references
`RDB$VIEW_CONTEXT`	`SMALLINT`	The alias used to reference the view column in the BLR code of the query definition
`RDB$CONTEXT_NAME`	`CHAR(255)`	The text associated with the alias reported in the `RDB$VIEW_CONTEXT` column