> * Prevent to_char() on interval from returning meaningless values
>
> For example, to_char('1 month', 'mon') is meaningless. Basically,
> most date-related parameters to to_char() are meaningless for
> intervals because interval is not anchored to a date.
>
> * Allow to_char() on interval values to accumulate the highest unit
> requested
>
> o to_char(INTERVAL '1 hour 5 minutes', 'MI') => 65
> o to_char(INTERVAL '43 hours 20 minutes', 'MI' ) => 2600
> o to_char(INTERVAL '43 hours 20 minutes', 'WK:DD:HR:MI') => 0:1:19:20
> o to_char(INTERVAL '3 years 5 months','MM') => 41
>
> Some special format flag would be required to request such
> accumulation. Such functionality could also be added to EXTRACT.
> Prevent accumulation that crosses the month/day boundary because of
> the uneven number of days in a month.
>
< * Allow ORDER BY ... LIMIT 1 to select high/low value without sort or
> * Allow ORDER BY ... LIMIT # to select high/low value without sort or
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< Right now, if no index exists, ORDER BY ... LIMIT 1 requires we sort
> Right now, if no index exists, ORDER BY ... LIMIT # requires we sort
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> MIN/MAX already does this, but not for LIMIT > 1.
> * Allow ORDER BY ... LIMIT 1 to select high/low value without sort or
> index using a sequential scan for highest/lowest values
>
> Right now, if no index exists, ORDER BY ... LIMIT 1 requires we sort
> all values to return the high/low value. Instead The idea is to do a
> sequential scan to find the high/low value, thus avoiding the sort.
>
> One possible implementation is to start sequential scans from the lowest
> numbered buffer in the shared cache, and when reaching the end wrap
> around to the beginning, rather than always starting sequential scans
> at the start of the table.
< This allows vacuum to reclaim free space without requiring
< a sequential scan
> This allows vacuum to target specific pages for possible free space
> without requiring a sequential scan.
< * Consider parallel processing a single query
<
< This would involve using multiple threads or processes to do optimization,
< sorting, or execution of single query. The major advantage of such a
< feature would be to allow multiple CPUs to work together to process a
< single query.
<
< * Allow ORDER BY ... LIMIT 1 to select high/low value without sort or
< index using a sequential scan for highest/lowest values
<
< If only one value is needed, there is no need to sort the entire
< table. Instead a sequential scan could get the matching value.
<
< Solaris) might benefit from threading.
> Solaris) might benefit from threading. Also explore the idea of
> a single session using multiple threads to execute a query faster.
< Currently indexes do not have enough tuple tuple visibility
< information to allow data to be pulled from the index without
< also accessing the heap. One way to allow this is to set a bit
< to index tuples to indicate if a tuple is currently visible to
< all transactions when the first valid heap lookup happens. This
< bit would have to be cleared when a heap tuple is expired.
> Currently indexes do not have enough tuple visibility information
> to allow data to be pulled from the index without also accessing
> the heap. One way to allow this is to set a bit to index tuples
> to indicate if a tuple is currently visible to all transactions
> when the first valid heap lookup happens. This bit would have to
> be cleared when a heap tuple is expired.
< Bitmap indexes index single columns that can be combined with other bitmap
< indexes to dynamically create a composite index to match a specific query.
< Each index is a bitmap, and the bitmaps are bitwise AND'ed or OR'ed to be
< combined. They can index by tid or can be lossy requiring a scan of the
< heap page to find matching rows, or perhaps use a mixed solution where
< tids are recorded for pages with only a few matches and per-page bitmaps
< are used for more dense pages. Another idea is to use a 32-bit bitmap
< for every page and set a bit based on the item number mod(32).
> This feature allows separate indexes to be ANDed or ORed together. This
> is particularly useful for data warehousing applications that need to
> query the database in an many permutations. This feature scans an index
> and creates an in-memory bitmap, and allows that bitmap to be combined
> with other bitmap created in a similar way. The bitmap can either index
> all TIDs, or be lossy, meaning it records just page numbers and each
> page tuple has to be checked for validity in a separate pass.
< failure.
> failure. This could be triggered by a user command or a timer.
< * Force archiving of partially-full WAL files when pg_stop_backup() is
< called or the server is stopped
> * Automatically force archiving of partially-filled WAL files when
> pg_stop_backup() is called or the server is stopped
< * Add ANSI INTERVAL handling
> * Add ISo INTERVAL handling
< o Interpret syntax that isn't uniquely ANSI or PG, like '1:30' or
< '1' as ANSI syntax, e.g. interpret '1:30' MINUTE TO SECOND as
> o Interpret syntax that isn't uniquely ISO or PG, like '1:30' or
> '1' as ISO syntax, e.g. interpret '1:30' MINUTE TO SECOND as
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< * Add pre-parsing phase that converts non-ANSI syntax to supported
> * Add pre-parsing phase that converts non-ISO syntax to supported
< o Process mixed ANSI/PG syntax, and round value to requested
< precision or generate an error
< o Interpret INTERVAL '1 year' MONTH as CAST (INTERVAL '1 year' AS
< INTERVAL MONTH), and this should return '12 months'
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> o Interpret INTERVAL '1 year' MONTH as CAST (INTERVAL '1 year' AS
> INTERVAL MONTH), and this should return '12 months'
> o Round or truncate values to the requested precision, e.g.
> INTERVAL '11 months' AS YEAR should return one or zero
< o Add support for day-time syntax, INTERVAL '1 2:03:04'
> o Add support for day-time syntax, INTERVAL '1 2:03:04'
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< o Interpret INTERVAL '1:30' MINUTE TO SECOND as '1 minute 30 seconds'
> o Interpret syntax that isn't uniquely ANSI or PG, like '1:30' or
> '1' as ANSI syntax, e.g. interpret '1:30' MINUTE TO SECOND as
> '1 minute 30 seconds'
< * Add support for ANSI time INTERVAL syntax, INTERVAL '1 2:03:04' DAY TO SECOND
< * Add support for ANSI date INTERVAL syntax, INTERVAL '20-6' YEAR TO MONTH
< * Process mixed ANSI/PG INTERVAL syntax, and round value to requested precision
<
< Interpret INTERVAL '1 year' MONTH as CAST (INTERVAL '1 year' AS INTERVAL
< MONTH), and this should return '12 months'
<
< * Interpret INTERVAL '1:30' MINUTE TO SECOND as '1 minute 30 seconds'
> * Add ANSI INTERVAL handling
> o Add support for day-time syntax, INTERVAL '1 2:03:04'
> DAY TO SECOND
> o Add support for year-month syntax, INTERVAL '50-6' YEAR TO MONTH
> o Process mixed ANSI/PG syntax, and round value to requested
> precision or generate an error
> o Interpret INTERVAL '1 year' MONTH as CAST (INTERVAL '1 year' AS
> INTERVAL MONTH), and this should return '12 months'
> o Interpret INTERVAL '1:30' MINUTE TO SECOND as '1 minute 30 seconds'
> o Support precision, CREATE TABLE foo (a INTERVAL MONTH(3))
< * Add support for ANSI date INTERVAL syntax, INTERVAL '9-3' YEAR TO MONTH
> * Add support for ANSI date INTERVAL syntax, INTERVAL '20-6' YEAR TO MONTH
< * Add support for ANSI date INTERVAL syntax, INTERVAL '1-2' YEAR TO MONTH
> * Add support for ANSI date INTERVAL syntax, INTERVAL '9-3' YEAR TO MONTH
> * Add support for ANSI time INTERVAL syntax, INTERVAL '1 2:03:04' DAY TO SECOND
> * Add support for ANSI date INTERVAL syntax, INTERVAL '1-2' YEAR TO MONTH
> * Process mixed ANSI/PG INTERVAL syntax, and round value to requested precision
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> Interpret INTERVAL '1 year' MONTH as CAST (INTERVAL '1 year' AS INTERVAL
> MONTH), and this should return '12 months'
Bruce Momjian