.qtk.tbl

.qtk.tbl.addColumn¶

Add a column to a table with a given value.

Parameters:

Name	Type	Description
tabRef	symbol \| hsym \| (hsym; symbol; symbol)	Table reference.
column	symbol	Name of new column to be added.
columnValue	any	Value to be set on the new column.

Returns:

Type	Description
symbol \| hsym \| (hsym; symbol; symbol)	The table reference.

Throws:

Type	Description
ColumnNameError	If `column` is not a valid name.
ColumnExistsError	If `column` already exists.

Example:

 system "l ",getenv[`QTK],"/init.q";
 .qtk.import.loadModule["tbl";`qtk];
 tabRef:(`:/tmp/qtk/tbl/addColumn; `date; `PartitionedTable);
 .qtk.tbl.create[tabRef; ([] date:2022.01.01 2022.01.02; c1:1 2)];

 // Or replace tabRef with `PartitionedTable if the database is loaded
 tabRef~.qtk.tbl.addColumn[tabRef; `c2; 0n]

.qtk.tbl.apply¶

Apply a function to a column of a table.

Parameters:

Name	Type	Description
tabRef	symbol \| hsym \| (hsym; symbol; symbol)	Table reference.
column	symbol	Column where the function will be applied.
function	fn (any[]) → any[]	Function to be applied.

Returns:

Type	Description
symbol \| hsym \| (hsym; symbol; symbol)	The table reference.

Throws:

Type	Description
ColumnNotFoundError	If `column` doesn't exist.

Example:

 system "l ",getenv[`QTK],"/init.q";
 .qtk.import.loadModule["tbl";`qtk];
 tabRef:(`:/tmp/qtk/tbl/apply; `date; `PartitionedTable);
 .qtk.tbl.create[tabRef; ([] date:2022.01.01 2022.01.02; c1:1 2)];

 // Or replace tabRef with `PartitionedTable if the database is loaded
 tabRef~.qtk.tbl.apply[tabRef; `c1; 2*]

.qtk.tbl.at¶

Get entries at given indices of a table. It's similar to .Q.ind but has the following differences:

if indices are empty, an empty table of conforming schema is returned rather than an empty list.
if indices go out of bound, an empty table of conforming schema is returned rather than raising 'par error

Parameters:

Name	Type	Description
table	symbol \| hsym \| table	Table name, path or value.
indices	int[] \| long[]	Indices to select from.

Returns:

Type	Description
table	Table at the given indices.

.qtk.tbl.castColumn¶

Cast the datatype of a column of a table.

Parameters:

Name	Type	Description
tabRef	symbol \| hsym \| (hsym; symbol; symbol)	Table reference.
column	symbol	Column whose datatype will be casted.
newType	symbol \| char	Name or character code of the new data type.

Returns:

Type	Description
symbol \| hsym \| (hsym; symbol; symbol)	The table reference.

Throws:

Type	Description
ColumnNotFoundError	If `column` doesn't exist.

Example:

 system "l ",getenv[`QTK],"/init.q";
 .qtk.import.loadModule["tbl";`qtk];
 tabRef:(`:/tmp/qtk/tbl/castColumn; `date; `PartitionedTable);
 .qtk.tbl.create[tabRef; ([] date:2022.01.01 2022.01.02; c1:1 2)];

 // Or replace tabRef with `PartitionedTable if the database is loaded
 tabRef~.qtk.tbl.castColumn[tabRef; `c1; `int]

.qtk.tbl.columnExists¶

Check if a column exists in a table. For splayed tables, column existence requires that the column appears in .d file and its data file exists. For partitioned tables, it requires the condition holds for the latest partition.

Parameters:

Name	Type	Description
table	table \| symbol \| hsym \| (hsym; symbol; symbol)	Table value or reference.
column	symbol	Column name.

Returns:

Type	Description
boolean	`1b` if the column exists in the table; `0b` otherwise.

Example:

 system "l ",getenv[`QTK],"/init.q";
 .qtk.import.loadModule["tbl";`qtk];
 tabRef:(`:/tmp/qtk/tbl/columnExists; `date; `PartitionedTable);
 .qtk.tbl.create[tabRef; ([] date:2022.01.01 2022.01.02; c1:1 2)];

 // Or replace tabRef with `PartitionedTable if the database is loaded
 .qtk.tbl.columnExists[tabRef;`c1]

.qtk.tbl.columns¶

Get column names of a table. It's similar to cols but supports all table types. For partitioned table, the latest partition is used.

Parameter:

Name	Type	Description
t	table \| symbol \| hsym \| (hsym; symbol; symbol)	Table or table reference.

Returns:

Type	Description
symbol[]	Column names.

Example:

 system "l ",getenv[`QTK],"/init.q";
 .qtk.import.loadModule["tbl";`qtk];
 tabRef:(`:/tmp/qtk/tbl/columns; `date; `PartitionedTable);
 .qtk.tbl.create[tabRef; ([] date:2022.01.01 2022.01.02; c1:1 2; c2:`a`b)];

 // Or replace tabRef with `PartitionedTable if the database is loaded
 `date`c1`c2~.qtk.tbl.columns tabRef

.qtk.tbl.copyColumn¶

Copy an existing column of a table to a new column.

Parameters:

Name	Type	Description
tabRef	symbol \| hsym \| (hsym; symbol; symbol)	Table reference.
sourceColumn	symbol	Source column to copy from.
targetColumn	symbol	Target column to copy to.

Returns:

Type	Description
symbol \| hsym \| (hsym; symbol; symbol)	The table reference.

Throws:

Type	Description
ColumnNotFoundError	If `sourceColumn` doesn't exist.
ColumnExistsError	If `targetColumn` exists.
ColumnNameError	If name of `targetColumn` is not valid.

Example:

 system "l ",getenv[`QTK],"/init.q";
 .qtk.import.loadModule["tbl";`qtk];
 tabRef:(`:/tmp/qtk/tbl/copyColumn; `date; `PartitionedTable);
 .qtk.tbl.create[tabRef; ([] date:2022.01.01 2022.01.02; c1:1 2)];

 // Or replace tabRef with `PartitionedTable if the database is loaded
 .qtk.tbl.copyColumn[tabRef; `c1; `c2];
 .qtk.tbl.columnExists[tabRef; `c2]

.qtk.tbl.count¶

Count rows of a table. It's similar to count but supports all table types.

Parameter:

Name	Type	Description
table	table \| symbol \| hsym \| (hsym; symbol; symbol)	Table value or reference.

Returns:

Type	Description
long	Row count of the table.

Example:

 system "l ",getenv[`QTK],"/init.q";
 .qtk.import.loadModule["tbl";`qtk];
 tabRef:(`:/tmp/qtk/tbl/count; `date; `PartitionedTable);
 .qtk.tbl.create[tabRef; ([] date:2022.01.01 2022.01.02; c1:1 2)];

 // Or replace tabRef with `PartitionedTable if the database is loaded
 2=.qtk.tbl.count tabRef

.qtk.tbl.create¶

Create a new table with given data.

Parameters:

Name	Type	Description
tabRef	symbol \| hsym \| (hsym; symbol; symbol)	Table reference.
data	table	Table data.

Returns:

Type	Description
symbol \| hsym \| (hsym; symbol; symbol)	The table reference.

Example:

 system "l ",getenv[`QTK],"/init.q";
 .qtk.import.loadModule["tbl";`qtk];
 tabRef:(`:/tmp/qtk/tbl/create; `date; `PartitionedTable);

 tabRef~.qtk.tbl.create[tabRef; ([] date:2022.01.01 2022.01.02; c1:1 2)]

.qtk.tbl.deleteColumn¶

Delete a column from a table.

Parameters:

Name	Type	Description
tabRef	symbol \| hsym \| (hsym; symbol; symbol)	Table reference.
column	symbol	A column to be deleted.

Returns:

Type	Description
symbol \| hsym \| (hsym; symbol; symbol)	The table reference.

Example:

 system "l ",getenv[`QTK],"/init.q";
 .qtk.import.loadModule["tbl";`qtk];
 tabRef:(`:/tmp/qtk/tbl/deleteColumn; `date; `PartitionedTable);
 .qtk.tbl.create[tabRef; ([] date:2022.01.01 2022.01.02; c1:1 2; c2:`a`b)];

 // Or replace tabRef with `PartitionedTable if the database is loaded
 tabRef~.qtk.tbl.deleteColumn[tabRef; `c2]

.qtk.tbl.deleteRows¶

Delete rows of a table given certain criteria.

Parameters:

Name	Type	Description
tabRef	symbol \| hsym \| (hsym; symbol; symbol)	Table reference.
criteria	any[]	A list of criteria where matching rows will be deleted, or empty list to delete all rows. For partitioned tables, if partition field is included in the criteria, it has to be the first in the list.

Returns:

Type	Description
tabRef	The table reference.

Example:

 system "l ",getenv[`QTK],"/init.q";
 .qtk.import.loadModule["tbl";`qtk];
 tabRef:(`:/tmp/qtk/tbl/deleteRows; `date; `PartitionedTable);
 .qtk.tbl.create[tabRef; ([] date:2022.01.01 2022.01.02 2022.01.02; c1:1 2 3)];

 // Or replace tabRef with `PartitionedTable if the database is loaded
 tabRef~.qtk.tbl.deleteRows[tabRef; enlist(=;`c1;3)]

.qtk.tbl.describe¶

Describe a table reference.

Parameter:

Name	Type	Description
tabRef	symbol \| hsym \| (hsym; symbol; symbol)	Table reference.

Returns:

Name	Type	Description
description	dict	A dictionary describing the table reference.
description.type	symbol	Table type.
description.name	symbol	Table name.
description.dbDir	hsym	Database directory, or null symbol if not applicable.
description.parField	symbol	Partition field or null symbol if not applicable.

Throws:

Type	Description
TypeError	If `tabRef` is not of valid type.

Example:

 system "l ",getenv[`QTK],"/init.q";
 .qtk.import.loadModule["tbl";`qtk];
 tabRef:(`:/tmp/qtk/tbl/describe; `date; `PartitionedTable);
 .qtk.tbl.create[tabRef; ([] date:2022.01.01 2022.01.02; c1:1 2)];

 // Or replace tabRef with `PartitionedTable if the database is loaded
 (`type`name`dbDir`parField!(`Partitioned; `PartitionedTable; `:/tmp/qtk/tbl/describe ; `date))~.qtk.tbl.describe tabRef

.qtk.tbl.drop¶

Drop a table.

Parameter:

Name	Type	Description
tabRef	symbol \| hsym \| (hsym; symbol; symbol)	Table reference.

Returns:

Type	Description
symbol \| hsym \| (hsym; symbol; symbol)	The table reference.

Example:

 system "l ",getenv[`QTK],"/init.q";
 .qtk.import.loadModule["tbl";`qtk];
 tabRef:(`:/tmp/qtk/tbl/drop; `date; `PartitionedTable);
 .qtk.tbl.create[tabRef; ([] date:2022.01.01 2022.01.02; c1:1 2)];

 // Or replace tabRef with `PartitionedTable if the database is loaded
 tabRef~.qtk.tbl.drop tabRef

.qtk.tbl.exists¶

Check if a table of given name exists. For splayed table not in the current database, it's deemed existent if the directory exists. For partitioned table not in the current database, it's deemed existent if the directory exists in either the first or the last partition.

Parameter:

Name	Type	Description
tabRef	symbol \| hsym \| (hsym; symbol; symbol)	Table reference.

Returns:

Type	Description
boolean	`1b` if the table exists; `0b` otherwise.

Example:

 system "l ",getenv[`QTK],"/init.q";
 .qtk.import.loadModule["tbl";`qtk];
 tabRef:(`:/tmp/qtk/tbl/exists; `date; `PartitionedTable);
 .qtk.tbl.create[tabRef; ([] date:2022.01.01 2022.01.02; c1:1 2)];

 // Or replace tabRef with `PartitionedTable if the database is loaded
 .qtk.tbl.exists tabRef

.qtk.tbl.fix¶

Fix a partitioned table based on a good partition. Fixable issues include:

add .d file if missing
add missing columns to .d file
add missing data files to disk filled by nulls for simple columns or empty lists for compound columns
remove excessive columns from .d file but leave data files untouched
put columns in the right order

Parameters:

Name	Type	Description
tabRef	symbol \| (hsym; symbol; symbol)	Table reference.
refPartition	date \| month \| int	A good partition to which the fixing refers.

Returns:

Type	Description
symbol \| (hsym; symbol; symbol)	The table reference.

Throws:

Type	Description
NotAPartitionedTableError	If the table is not a partitioned table.

Example:

 system "l ",getenv[`QTK],"/init.q";
 .qtk.import.loadModule["tbl";`qtk];
 tabRef:(`:/tmp/qtk/tbl/fix; `date; `PartitionedTable);
 .qtk.tbl.create[tabRef; ([] date:2022.01.01 2022.01.02; c1:1 2)];
 .qtk.os.remove "/tmp/qtk/tbl/fix/2022.01.02/Table/.d";

 // Or replace tabRef with `PartitionedTable if the database is loaded
 tabRef~.qtk.tbl.fix[tabRef; 2022.01.01]

.qtk.tbl.foreignKeys¶

Get foreign keys of a table. It's similar to fkeys but supports table name besides value. For partitioned table, the latest partition is used. Note that this is supported only for the current database.

Parameter:

Name	Type	Description
t	table \| symbol	Table or table name.

Returns:

Type	Description
dict	A dictionary that maps foreign-key columns to their tables.

.qtk.tbl.getAttr¶

Get attributes of a table. It's an extended from of attr that is applicable to tables.

Parameter:

Name	Type	Description
tabRef	symbol \| hsym \| (hsym; symbol; symbol)	Table reference.

Returns:

Type	Description
dict	A mapping from columns names to attributes, where columns without attributes are not included.

Example:

 system "l ",getenv[`QTK],"/init.q";
 .qtk.import.loadModule["tbl";`qtk];
 tabRef:(`:/tmp/qtk/tbl/getAttr; `date; `PartitionedTable);
 .qtk.tbl.create[tabRef; ([] date:2022.01.01 2022.01.02; c1:1 2)];
 .qtk.tbl.setAttr[tabRef; enlist[`c1]!enlist[`s]];

 // Or replace tabRef with `PartitionedTable if the database is loaded
 (enlist[`c1]!enlist[`s])~.qtk.tbl.getAttr tabRef

.qtk.tbl.getType¶

Get table type, either of `Plain`Serialized`Splayed`Partitioned. Note that tables in segmented database are classified as Partitioned.

See also .Q.qp.

Parameter:

Name	Type	Description
t	table \| symbol \| hsym \| (hsym; symbol; symbol)	Table or table reference.

Returns:

Type	Description
symbol	Table type.

Throws:

Type	Description
ValueError	If `t` is a symbol vector but not a valid partitioned table ID.

Example:

 system "l ",getenv[`QTK],"/init.q";
 .qtk.import.loadModule["tbl";`qtk];
 tabRef:(`:/tmp/qtk/tbl/getType; `date; `PartitionedTable);
 .qtk.tbl.create[tabRef; ([] date:2022.01.01 2022.01.02; c1:1 2)];

 // Or replace tabRef with `PartitionedTable if the database is loaded
 `Partitioned=.qtk.tbl.getType tabRef

.qtk.tbl.insert¶

Insert data into a table. For partitioned tables, data need to be sorted by partitioned field. Partial data are acceptable; the missing columns will be filled by type compliant nulls for simple columns or empty lists for compound columns.

Parameters:

Name	Type	Description
tabRef	symbol \| hsym \| (hsym; symbol; symbol)	Table reference
data	table	Table data.

Returns:

Type	Description
symbol \| hsym \| (hsym; symbol; symbol)	The table reference.

Example:

 system "l ",getenv[`QTK],"/init.q";
 .qtk.import.loadModule["tbl";`qtk];
 tabRef:(`:/tmp/qtk/tbl/insert; `date; `PartitionedTable);
 .qtk.tbl.create[tabRef; ([] date:2022.01.01 2022.01.02; c1:1 2)];

 // Or replace tabRef with `PartitionedTable if the database is loaded
 tabRef~.qtk.tbl.insert[tabRef; ([] date:2022.01.03 2022.01.04; c1:3 4)]

.qtk.tbl.keepAttr¶

Wrap a function that modifies a table but keep the original attributes.

Parameter:

Name	Type	Description
func	func	A function that modifies a table.

Returns:

Type	Description
func	A wrapper function that keeps the original attributes.

.qtk.tbl.key¶

Return the key of a table if it's keyed table, or generic null otherwise. It's an alias of key.

Parameter:

Name	Type	Description
t	table \| symbol \| hsym \| (hsym; symbol; symbol)	Table or table reference.

Returns:

Type	Description
table \| ::	Key of the table.

Example:

 system "l ",getenv[`QTK],"/init.q";
 .qtk.import.loadModule["tbl";`qtk];

 ([] c1:`a`b)~.qtk.tbl.key ([c1:`a`b] c2:1 2)

.qtk.tbl.meta¶

Get metadata of a table. It's similar to meta but supports all table types. For partitioned table, the latest partition is used.

Parameter:

Name	Type	Description
t	table \| symbol \| hsym \| (hsym; symbol; symbol)	Table or table reference.

Returns:

Type	Description
table	Metadata of the table.

Example:

 system "l ",getenv[`QTK],"/init.q";
 .qtk.import.loadModule["tbl";`qtk];
 tabRef:(`:/tmp/qtk/tbl/meta; `date; `PartitionedTable);
 .qtk.tbl.create[tabRef; ([] date:2022.01.01 2022.01.02; c1:1 2)];

 // Or replace tabRef with `PartitionedTable if the database is loaded
 ([c:`date`c1] t:"dj"; f:`; a:`)~.qtk.tbl.meta tabRef

.qtk.tbl.raiseIfColumnExists¶

Raise ColumnExistsError if a column exists in a table.

Parameters:

Name	Type	Description
table	table \| symbol \| hsym \| (hsym; symbol; symbol)	Table value or reference.
column	symbol	A column name.

Throws:

Type	Description
ColumnExistsError	If the column exists.

Example:

 system "l ",getenv[`QTK],"/init.q";
 .qtk.import.loadModule["tbl";`qtk];
 tabRef:(`:/tmp/qtk/tbl/raiseIfColumnExists; `date; `PartitionedTable);
 .qtk.tbl.create[tabRef; ([] date:2022.01.01 2022.01.02; c1:1 2)];

 // Or replace tabRef with `PartitionedTable if the database is loaded
 "ColumnExistsError: c1 on :/tmp/qtk/tbl/raiseIfColumnExists/date/PartitionedTable"~.[.qtk.tbl.raiseIfColumnExists; (tabRef; `c1); {x}]

.qtk.tbl.raiseIfColumnNameInvalid¶

Raise ColumnNameError if a column name is not valid, i.e. it collides with q's reserved words and implicit column i.

Parameter:

Name	Type	Description
name	symbol	A column name.

Throws:

Type	Description
ColumnNameError	If the column name is not valid.

Example:

 system "l ",getenv[`QTK],"/init.q";
 .qtk.import.loadModule["tbl";`qtk];

 "ColumnNameError: abs"~@[.qtk.tbl.raiseIfColumnNameInvalid; `abs; {x}]

.qtk.tbl.raiseIfColumnNotFound¶

Raise ColumnNotFoundError if a column is not found from a table.

Parameters:

Name	Type	Description
table	table \| symbol \| hsym \| (hsym; symbol; symbol)	Table value or reference.
column	symbol	A column name.

Throws:

Type	Description
ColumnNotFoundError	If the column doesn't exist.

Example:

 system "l ",getenv[`QTK],"/init.q";
 .qtk.import.loadModule["tbl";`qtk];
 tabRef:(`:/tmp/qtk/tbl/raiseIfColumnNotFound; `date; `PartitionedTable);
 .qtk.tbl.create[tabRef; ([] date:2022.01.01 2022.01.02; c1:1 2)];

 // Or replace tabRef with `PartitionedTable if the database is loaded
 "ColumnNotFoundError: c2 on :/tmp/qtk/tbl/raiseIfColumnNotFound/date/PartitionedTable"~.[.qtk.tbl.raiseIfColumnNotFound; (tabRef; `c2); {x}]

.qtk.tbl.rename¶

Rename a table.

Parameters:

Name	Type	Description
tabRef	symbol \| hsym \| (hsym; symbol; symbol)	Table reference.
newName	symbol	New name of the table.

Returns:

Type	Description
symbol \| hsym \| (hsym; symbol; symbol)	New table reference.

Throws:

Type	Description
TableNameError	If the table name is not valid, i.e. it collides with q's reserved words
NameExistsError	If the name is in use

Example:

 system "l ",getenv[`QTK],"/init.q";
 .qtk.import.loadModule["tbl";`qtk];
 tabRef:(`:/tmp/qtk/tbl/rename; `date; `PartitionedTable);
 .qtk.tbl.create[tabRef; ([] date:2022.01.01 2022.01.02; c1:1 2)];

 // Or replace tabRef with `PartitionedTable if the database is loaded
 (`:/tmp/qtk/tbl/rename; `date; `NewPartitionedTable)~.qtk.tbl.rename[tabRef; `NewPartitionedTable]

.qtk.tbl.renameColumns¶

Rename column(s) from a table.

Parameters:

Name	Type	Description
tabRef	symbol \| hsym \| (hsym; symbol; symbol)	Table name.
nameDict	dict	A dictionary from existing name(s) to new name(s).

Returns:

Type	Description
symbol \| hsym \| (hsym; symbol; symbol)	The table reference.

Throws:

Type	Description
ColumnNameError	If the column name is not valid.
ColumnNotFoundError	If some column doesn't exist.

Example:

 system "l ",getenv[`QTK],"/init.q";
 .qtk.import.loadModule["tbl";`qtk];
 tabRef:(`:/tmp/qtk/tbl/renameColumns; `date; `PartitionedTable);
 .qtk.tbl.create[tabRef; ([] date:2022.01.01 2022.01.02; c1:1 2; c2:`a`b)];

 // Or replace tabRef with `PartitionedTable if the database is loaded
 tabRef~.qtk.tbl.renameColumns[tabRef; `c1`c2!`c3`c4]

.qtk.tbl.reorderColumns¶

Reorder columns of a table.

Parameters:

Name	Type	Description
tabRef	symbol \| hsym \| (hsym; symbol; symbol)	Table reference.
firstColumns	symbol[]	First columns after reordering.

Returns:

Type	Description
symbol \| hsym \| (hsym; symbol; symbol)	The table reference.

Throws:

Type	Description
ColumnNotFoundError	If some column in `firstColumns` doesn't exist.

Example:

 system "l ",getenv[`QTK],"/init.q";
 .qtk.import.loadModule["tbl";`qtk];
 tabRef:(`:/tmp/qtk/tbl/reorderColumns; `date; `PartitionedTable);
 .qtk.tbl.create[tabRef; ([] date:2022.01.01 2022.01.02; c1:1 2; c2:`a`b)];

 // Or replace tabRef with `PartitionedTable if the database is loaded
 tabRef~.qtk.tbl.reorderColumns[tabRef; `c2]

.qtk.tbl.select¶

Select from a table similar to functional select but support all table types.

Parameters:

Name	Type	Description
table	table \| symbol \| hsym	Table name, path or value.
criteria	any[]	A list of criteria where the select is applied to, or empty list for the whole table.
groupings	dict \| boolean	A mapping of grouping columns, or `0b` for no grouping, `1b` for distinct.
columns	dict	Mappings from column names to columns/expressions.

Returns:

Type	Description
table	Selected data from the table.

.qtk.tbl.selectLimit¶

Select from a table similar to rank-5 functional select but support all table types.

Parameters:

Name	Type	Description
table	table \| symbol \| hsym	Table name, path or value.
criteria	any[]	A list of criteria where the select is applied to, or empty list for the whole table.
groupings	dict \| boolean	A mapping of grouping columns, or `0b` for no grouping, `1b` for distinct.
columns	dict	Mappings from column names to columns/expressions.
limit	int \| long \| (int; int) \| (long; long)	Limit on rows to return.

Returns:

Type	Description
table	Selected data from the table.

.qtk.tbl.selectLimitSort¶

Select from a table similar to rank-6 functional select but support all table types.

Parameters:

Name	Type	Description
table	table \| symbol \| hsym	Table name, path or value.
criteria	any[]	A list of criteria where the select is applied to, or empty list for the whole table.
groupings	dict \| boolean	A mapping of grouping columns, or `0b` for no grouping, `1b` for distinct.
columns	dict	Mappings from column names to columns/expressions.
limit	int \| long \| (int; int) \| (long; long)	Limit on rows to return.
sort	any[]	Sort the result by a column. The format is `(op;col)` where `op` is `>:` for descending and `<:` for ascending, and `col` is the column to be ordered by.

Returns:

Type	Description
table	Selected data from the table.

.qtk.tbl.setAttr¶

Set attributes to a table. It's an extended form of Set Attribute that is applicable to tables.

Parameters:

Name	Type	Description
tabRef	symbol \| hsym \| (hsym; symbol; symbol)	Table reference.
attrs	dict	A mapping from column names to attributes.

Returns:

Type	Description
symbol \| hsym \| (hsym; symbol; symbol)	The table reference.

Throws:

Type	Description
ColumnNotFoundError	If some columns in `attrs` don't exist.

Example:

 system "l ",getenv[`QTK],"/init.q";
 .qtk.import.loadModule["tbl";`qtk];
 tabRef:(`:/tmp/qtk/tbl/setAttr; `date; `PartitionedTable);
 .qtk.tbl.create[tabRef; ([] date:2022.01.01 2022.01.02; c1:1 2)];

 // Or replace tabRef with `PartitionedTable if the database is loaded
 .qtk.tbl.setAttr[tabRef; enlist[`c1]!enlist[`s]];
 `s=.qtk.tbl.meta[tabRef][`c1;`a]

.qtk.tbl.update¶

Update values in certain columns of a table, similar to functional update but support all table types.

Parameters:

Name	Type	Description
tabRef	symbol \| hsym \| (hsym; symbol; symbol)	Table reference.
criteria	any[]	A list of criteria where the select is applied to, or empty list for the whole table. For partitioned tables, if partition field is included in the criteria, it has to be the first in the list.
groupings	dict \| 0b	A mapping of grouping columns, or `0b` for no grouping.
columns	dict	Mappings from column names to columns/expressions.

Returns:

Type	Description
symbol \| hsym \| (hsym; symbol; symbol)	The table reference.

Throws:

Type	Description
ColumnNotFoundError	If a column from `columns` doesn't exist.