Also, the and * operators come in commutative pairs (for example both date integer and integer date) we show only one of each such pair. For brevity, these variants are not shown separately. Similarly, a date value is assumed to represent midnight in the TimeZone zone when comparing it to a timestamp.Īll the functions and operators described below that take time or timestamp inputs actually come in two variants: one that takes time with time zone or timestamp with time zone, and one that takes time without time zone or timestamp without time zone. When comparing a timestamp without time zone to a timestamp with time zone, the former value is assumed to be given in the time zone specified by the TimeZone configuration parameter, and is rotated to UTC for comparison to the latter value (which is already in UTC internally). Dates and timestamps (with or without time zone) are all comparable, while times (with or without time zone) and intervals can only be compared to other values of the same data type. In addition, the usual comparison operators shown in Table 9.1 are available for the date/time types. You should be familiar with the background information on date/time data types from Section 8.5. For formatting functions, refer to Section 9.8. Table 9.32 illustrates the behaviors of the basic arithmetic operators ( , *, etc.). Table 9.33 shows the available functions for date/time value processing, with details appearing in the following subsections. It won't use the index unless you use the same function in the queryĬREATE INDEX ON. Ken> index it still doesn't seem to use the index for queries. Ken> Yeah, I thought I might have to do that, but when I create that > would be to do your own fixed-format date parsing function (and > If you absolutely can't change the column type, then one option Then substring($1 from '^\d\d\d\d-?\d\d-?\d\d')::dateĬREATE INDEX ON export_hch_encounter_history ( iso_date("Service_Date")) ĬREATE INDEX ON export_hch_encounter_history ( make_date(LEFT("Service_Date",4)::int,SUBSTRING("Service_Date",6,2)::int,SUBSTRING("Service_Date",9,2)::int)) EXPLAIN ANALYZE SELECT * FROM export_hch_encounter_history WHERE "Service_Date"::date BETWEEN ''::date AND ''::date QUERY PLAN If you absolutely can't change the column type, then one option would be If the column type were timestamp, though, then you could do comparisonsĭirectly, or cast the value to "date" (which is an immutable cast). (again, you might know that you're not using those, but the code With to_date or to_timestamp and a fixed format, because those functionsĪre also mutable since some of the format options are locale-dependent You can't make this a field of type "timestamp" rather than text?Ĭasts from text to either date or timestamp are mutable because theyĭepend on the current DateStyle value (_you_ might know that your valuesĪre always ISO format, but the code doesn't). I've got a text field in a table that holds this style of > Is there any way, hacky or otherwise, people know of to do this? Thanks > etc.), but all of them throw the error "functions in index expressionĬan you also show the actual index expression? > I've tried various ways of getting to a date (::date, LEFT(x,10)::date, > (as a date), because I have lots of queries that are searching for > I'd like to be able to create an index on the date portion of this field I've got a text field in a table that holds this style of timestamp:
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