[jira] [Commented] (SPARK-31297) Speed-up date-time rebasing
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https://issues.apache.org/jira/browse/SPARK-31297?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=17070457#comment-17070457
]
Maxim Gekk commented on SPARK-31297:
The rebasing of days doesn't depend on time zone, and has just 14 special dates:
{code:scala}
test("optimize rebasing") {
val start = localDateToDays(LocalDate.of(1, 1, 1))
val end = localDateToDays(LocalDate.of(2030, 1, 1))
var days = start
var diff = Long.MaxValue
var counter = 0
while (days < end) {
val rebased = rebaseGregorianToJulianDays(days)
val curDiff = rebased - days
if (curDiff != diff) {
counter += 1
diff = curDiff
val ld = daysToLocalDate(days)
println(s"local date = $ld days = $days diff = ${diff} days")
}
days += 1
}
println(s"counter = $counter")
}
{code}
{code}
local date = 0001-01-01 days = -719162 diff = -2 days
local date = 0100-03-01 days = -682944 diff = -1 days
local date = 0200-03-01 days = -646420 diff = 0 days
local date = 0300-03-01 days = -609896 diff = 1 days
local date = 0500-03-01 days = -536847 diff = 2 days
local date = 0600-03-01 days = -500323 diff = 3 days
local date = 0700-03-01 days = -463799 diff = 4 days
local date = 0900-03-01 days = -390750 diff = 5 days
local date = 1000-03-01 days = -354226 diff = 6 days
local date = 1100-03-01 days = -317702 diff = 7 days
local date = 1300-03-01 days = -244653 diff = 8 days
local date = 1400-03-01 days = -208129 diff = 9 days
local date = 1500-03-01 days = -171605 diff = 10 days
local date = 1582-10-15 days = -141427 diff = 0 days
counter = 14
{code}
> Speed-up date-time rebasing
> ---
>
> Key: SPARK-31297
> URL: https://issues.apache.org/jira/browse/SPARK-31297
> Project: Spark
> Issue Type: Improvement
> Components: SQL
>Affects Versions: 3.0.0
>Reporter: Maxim Gekk
>Priority: Major
>
> I do believe it is possible to speed up date-time rebasing by building a map
> of micros to diffs between original and rebased micros. And look up at the
> map via binary search.
> For example, the *America/Los_Angeles* time zone has less than 100 points
> when diff changes:
> {code:scala}
> test("optimize rebasing") {
> val start = instantToMicros(LocalDateTime.of(1, 1, 1, 0, 0, 0)
> .atZone(getZoneId("America/Los_Angeles"))
> .toInstant)
> val end = instantToMicros(LocalDateTime.of(2030, 1, 1, 0, 0, 0)
> .atZone(getZoneId("America/Los_Angeles"))
> .toInstant)
> var micros = start
> var diff = Long.MaxValue
> var counter = 0
> while (micros < end) {
> val rebased = rebaseGregorianToJulianMicros(micros)
> val curDiff = rebased - micros
> if (curDiff != diff) {
> counter += 1
> diff = curDiff
> val ldt =
> microsToInstant(micros).atZone(getZoneId("America/Los_Angeles")).toLocalDateTime
> println(s"local date-time = $ldt diff = ${diff / MICROS_PER_MINUTE}
> minutes")
> }
> micros += MICROS_PER_HOUR
> }
> println(s"counter = $counter")
> }
> {code}
> {code:java}
> local date-time = 0001-01-01T00:00 diff = -2909 minutes
> local date-time = 0100-02-28T14:00 diff = -1469 minutes
> local date-time = 0200-02-28T14:00 diff = -29 minutes
> local date-time = 0300-02-28T14:00 diff = 1410 minutes
> local date-time = 0500-02-28T14:00 diff = 2850 minutes
> local date-time = 0600-02-28T14:00 diff = 4290 minutes
> local date-time = 0700-02-28T14:00 diff = 5730 minutes
> local date-time = 0900-02-28T14:00 diff = 7170 minutes
> local date-time = 1000-02-28T14:00 diff = 8610 minutes
> local date-time = 1100-02-28T14:00 diff = 10050 minutes
> local date-time = 1300-02-28T14:00 diff = 11490 minutes
> local date-time = 1400-02-28T14:00 diff = 12930 minutes
> local date-time = 1500-02-28T14:00 diff = 14370 minutes
> local date-time = 1582-10-14T14:00 diff = -29 minutes
> local date-time = 1899-12-31T16:52:58 diff = 0 minutes
> local date-time = 1917-12-27T11:52:58 diff = 60 minutes
> local date-time = 1917-12-27T12:52:58 diff = 0 minutes
> local date-time = 1918-09-15T12:52:58 diff = 60 minutes
> local date-time = 1918-09-15T13:52:58 diff = 0 minutes
> local date-time = 1919-06-30T16:52:58 diff = 31 minutes
> local date-time = 1919-06-30T17:52:58 diff = 0 minutes
> local date-time = 1919-08-15T12:52:58 diff = 60 minutes
> local date-time = 1919-08-15T13:52:58 diff = 0 minutes
> local date-time = 1921-08-31T10:52:58 diff = 60 minutes
> local date-time = 1921-08-31T11:52:58 diff = 0 minutes
> local date-time = 1921-09-30T11:52:58 diff = 60 minutes
> local date-time = 1921-09-30T12:52:58 diff = 0 minutes
> local date-time = 1922-09-30T12:52:58 diff = 60 minutes
> local date-time = 1922-09-30T13:52:58 diff = 0 minutes
> local date-time = 1981-09-30T12:52:58 diff = 60 minutes
> local date-time =
[jira] [Commented] (SPARK-31297) Speed-up date-time rebasing
[
https://issues.apache.org/jira/browse/SPARK-31297?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=17070286#comment-17070286
]
Maxim Gekk commented on SPARK-31297:
[~cloud_fan] [~hyukjin.kwon] [~dongjoon] WDYT?
> Speed-up date-time rebasing
> ---
>
> Key: SPARK-31297
> URL: https://issues.apache.org/jira/browse/SPARK-31297
> Project: Spark
> Issue Type: Improvement
> Components: SQL
>Affects Versions: 3.0.0
>Reporter: Maxim Gekk
>Priority: Major
>
> I do believe it is possible to speed up date-time rebasing by building a map
> of micros to diffs between original and rebased micros. And look up at the
> map via binary search.
> For example, the *America/Los_Angeles* time zone has less than 100 points
> when diff changes:
> {code:scala}
> test("optimize rebasing") {
> val start = instantToMicros(LocalDateTime.of(1, 1, 1, 0, 0, 0)
> .atZone(getZoneId("America/Los_Angeles"))
> .toInstant)
> val end = instantToMicros(LocalDateTime.of(2030, 1, 1, 0, 0, 0)
> .atZone(getZoneId("America/Los_Angeles"))
> .toInstant)
> var micros = start
> var diff = Long.MaxValue
> var counter = 0
> while (micros < end) {
> val rebased = rebaseGregorianToJulianMicros(micros)
> val curDiff = rebased - micros
> if (curDiff != diff) {
> counter += 1
> diff = curDiff
> val ldt =
> microsToInstant(micros).atZone(getZoneId("America/Los_Angeles")).toLocalDateTime
> println(s"local date-time = $ldt diff = ${diff / MICROS_PER_MINUTE}
> minutes")
> }
> micros += MICROS_PER_HOUR
> }
> println(s"counter = $counter")
> }
> {code}
> {code:java}
> local date-time = 0001-01-01T00:00 diff = -2909 minutes
> local date-time = 0100-02-28T14:00 diff = -1469 minutes
> local date-time = 0200-02-28T14:00 diff = -29 minutes
> local date-time = 0300-02-28T14:00 diff = 1410 minutes
> local date-time = 0500-02-28T14:00 diff = 2850 minutes
> local date-time = 0600-02-28T14:00 diff = 4290 minutes
> local date-time = 0700-02-28T14:00 diff = 5730 minutes
> local date-time = 0900-02-28T14:00 diff = 7170 minutes
> local date-time = 1000-02-28T14:00 diff = 8610 minutes
> local date-time = 1100-02-28T14:00 diff = 10050 minutes
> local date-time = 1300-02-28T14:00 diff = 11490 minutes
> local date-time = 1400-02-28T14:00 diff = 12930 minutes
> local date-time = 1500-02-28T14:00 diff = 14370 minutes
> local date-time = 1582-10-14T14:00 diff = -29 minutes
> local date-time = 1899-12-31T16:52:58 diff = 0 minutes
> local date-time = 1917-12-27T11:52:58 diff = 60 minutes
> local date-time = 1917-12-27T12:52:58 diff = 0 minutes
> local date-time = 1918-09-15T12:52:58 diff = 60 minutes
> local date-time = 1918-09-15T13:52:58 diff = 0 minutes
> local date-time = 1919-06-30T16:52:58 diff = 31 minutes
> local date-time = 1919-06-30T17:52:58 diff = 0 minutes
> local date-time = 1919-08-15T12:52:58 diff = 60 minutes
> local date-time = 1919-08-15T13:52:58 diff = 0 minutes
> local date-time = 1921-08-31T10:52:58 diff = 60 minutes
> local date-time = 1921-08-31T11:52:58 diff = 0 minutes
> local date-time = 1921-09-30T11:52:58 diff = 60 minutes
> local date-time = 1921-09-30T12:52:58 diff = 0 minutes
> local date-time = 1922-09-30T12:52:58 diff = 60 minutes
> local date-time = 1922-09-30T13:52:58 diff = 0 minutes
> local date-time = 1981-09-30T12:52:58 diff = 60 minutes
> local date-time = 1981-09-30T13:52:58 diff = 0 minutes
> local date-time = 1982-09-30T12:52:58 diff = 60 minutes
> local date-time = 1982-09-30T13:52:58 diff = 0 minutes
> local date-time = 1983-09-30T12:52:58 diff = 60 minutes
> local date-time = 1983-09-30T13:52:58 diff = 0 minutes
> local date-time = 1984-09-29T15:52:58 diff = 60 minutes
> local date-time = 1984-09-29T16:52:58 diff = 0 minutes
> local date-time = 1985-09-28T15:52:58 diff = 60 minutes
> local date-time = 1985-09-28T16:52:58 diff = 0 minutes
> local date-time = 1986-09-27T15:52:58 diff = 60 minutes
> local date-time = 1986-09-27T16:52:58 diff = 0 minutes
> local date-time = 1987-09-26T15:52:58 diff = 60 minutes
> local date-time = 1987-09-26T16:52:58 diff = 0 minutes
> local date-time = 1988-09-24T15:52:58 diff = 60 minutes
> local date-time = 1988-09-24T16:52:58 diff = 0 minutes
> local date-time = 1989-09-23T15:52:58 diff = 60 minutes
> local date-time = 1989-09-23T16:52:58 diff = 0 minutes
> local date-time = 1990-09-29T15:52:58 diff = 60 minutes
> local date-time = 1990-09-29T16:52:58 diff = 0 minutes
> local date-time = 1991-09-28T16:52:58 diff = 60 minutes
> local date-time = 1991-09-28T17:52:58 diff = 0 minutes
> local date-time = 1992-09-26T15:52:58 diff = 60 minutes
> local date-time = 1992-09-26T16:52:58 diff = 0 minutes
> local date-time = 1993-09-25T15:52:58 diff = 60 minutes
> local date-time = 1993-09-25T16:52:58 diff = 0
