result after all input data has been traversed. The function
must take a single argument of type
state_type.
- The output datatype of the aggregate is defined as the return
+ The output data type of the aggregate is defined as the return
type of this function.
If ffunc
is not specified, then the ending state value is used as the
The initial setting for the state value. This must be a literal
- constant in the form accepted for the datatype
+ constant in the form accepted for the data type
state_type.
If not specified, the state value starts out NULL.
that is, an initial value for the internal state value.
This is specified and stored in the database as a field of type
text, but it must be a valid external representation
- of a constant of the state value datatype. If it is not supplied
+ of a constant of the state value data type. If it is not supplied
then the state value starts out NULL.
four-byte integers would use the int4_ops class;
this operator class includes comparison functions for four-byte
integers. In practice the default operator class for the field's
- datatype is usually sufficient. The main point of having operator classes
- is that for some datatypes, there could be more than one meaningful
- ordering. For example, we might want to sort a complex-number datatype
+ data type is usually sufficient. The main point of having operator classes
+ is that for some data types, there could be more than one meaningful
+ ordering. For example, we might want to sort a complex-number data type
either by absolute value or by real part. We could do this by defining
- two operator classes for the datatype and then selecting the proper
+ two operator classes for the data type and then selecting the proper
class when making an index. There are also some operator classes with
special purposes:
The operator classes box_ops and
bigbox_ops both support rtree indices on the
- box datatype.
+ box data type.
The difference between them is that bigbox_ops
scales box coordinates down, to avoid floating point exceptions from
doing multiplication, addition, and subtraction on very large
the lines of [SHAP86]; however, it must know whether this
strategy is applicable. The current hash-join algorithm
is only correct for operators that represent equality tests;
- furthermore, equality of the datatype must mean bitwise equality
- of the representation of the type. (For example, a datatype that
+ furthermore, equality of the data type must mean bitwise equality
+ of the representation of the type. (For example, a data type that
contains unused bits that don't matter for equality tests could
not be hashjoined.)
The HASHES flag indicates to the query optimizer that a hash join
default
- The default value for the datatype. Usually this is omitted,
+ The default value for the data type. Usually this is omitted,
so that the default is NULL.
alignment
- Storage alignment requirement of the datatype. If specified, must
+ Storage alignment requirement of the data type. If specified, must
be 'int4' or 'double';
the default is 'int4'.
storage
- Storage technique for the datatype. If specified, must
+ Storage technique for the data type. If specified, must
be 'plain', 'external',
'extended', or 'main';
the default is 'plain'.
The storage keyword
- allows selection of TOAST storage method for variable-length datatypes
+ allows selection of TOAST storage method for variable-length data types
(only plain is allowed for fixed-length types).
- plain disables TOAST for the datatype: it will always
+ plain disables TOAST for the data type: it will always
be stored in-line and not compressed.
extended is full TOAST capability: the system will
first try to compress a long data value, and will move the value out of