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| author | Robert Haas <rhaas@postgresql.org> | 2017-01-04 16:30:16 -0500 |
|---|---|---|
| committer | Robert Haas <rhaas@postgresql.org> | 2017-01-04 16:30:16 -0500 |
| commit | 44f7afba79348883da110642d230a13003b75f62 (patch) | |
| tree | 22e16ebcb5e4667fe3a909eaace3e10dafd70474 | |
| parent | 3633b3f65686d3e74ab868e33bc25bec8bcdc7c6 (diff) | |
| download | postgresql-44f7afba79348883da110642d230a13003b75f62.tar.gz postgresql-44f7afba79348883da110642d230a13003b75f62.zip | |
Improve documentation of timestamp internal representation.
Be more clear that we represent timestamps in microseconds when
integer timestamps are used, and in fractional seconds when
floating-point timestamps are used.
Discussion: http://postgr.es/m/20161212135045.GB15488@e733.localdomain
Report by Alexander Alekseev. Wording by me with a suggestion
from Tom Lane.
| -rw-r--r-- | doc/src/sgml/datatype.sgml | 15 |
1 files changed, 8 insertions, 7 deletions
diff --git a/doc/src/sgml/datatype.sgml b/doc/src/sgml/datatype.sgml index 464ce83d30e..3bc6854be65 100644 --- a/doc/src/sgml/datatype.sgml +++ b/doc/src/sgml/datatype.sgml @@ -1651,13 +1651,14 @@ SELECT E'\\xDEADBEEF'; <para> When <type>timestamp</> values are stored as eight-byte integers (currently the default), microsecond precision is available over - the full range of values. When <type>timestamp</> values are - stored as double precision floating-point numbers instead (a - deprecated compile-time option), the effective limit of precision - might be less than 6. <type>timestamp</type> values are stored as - seconds before or after midnight 2000-01-01. When - <type>timestamp</type> values are implemented using floating-point - numbers, microsecond precision is achieved for dates within a few + the full range of values. In this case, the internal representation + is the number of microseconds before or after midnight 2000-01-01. + When <type>timestamp</> values are stored as double precision + floating-point numbers (a deprecated compile-time option), the + internal representation is the number of seconds before or after + midnight 2000-01-01. With this representation, the effective limit + of precision might be less than 6; in practice, + microsecond precision is achieved for dates within a few years of 2000-01-01, but the precision degrades for dates further away. Note that using floating-point datetimes allows a larger range of <type>timestamp</type> values to be represented than |