Add implementation of now, sysdate, localtime and similar functions

[Yury-Fridlyand]

Signed-off-by: Yury Fridlyand [email protected]

Description

New functions added:

• now()
• current_timestamp()
• localtimestamp()
• localtime()
• sysdate()
• curtime()
• current_time()
• curdate()
• current_date()

New signatures:

• now() : datetime
• current_timestamp() : datetime
• current_timestamp : datetime
• localtimestamp() : datetime
• localtimestamp : datetime
• localtime() : datetime
• localtime : datetime
• sysdate() : datetime
• sysdate(int) : datetime
• curtime() : time
• current_time() : time
• current_time : time
• curdate() : date
• current_date() : date
• current_date : date

Not added signatures

• now(int) : datetime
• current_timestamp(int) : datetime
• localtimestamp(int) : datetime
• localtime(int) : datetime
• curtime(int) : time
• current_time(int) : time

Tests

SQL

select now(), current_timestamp(), localtimestamp(), localtime(), sysdate(), sysdate(3), curdate(), curtime(), current_time(), current_date(), CURRENT_DATE, CURRENT_TIME, CURRENT_TIMESTAMP, LOCALTIME, LOCALTIMESTAMP;

fetched rows / total rows = 1/1
-[ RECORD 1 ]-------------------------
now()                   | 2022-07-20 20:15:25.262409
current_timestamp()     | 2022-07-20 20:15:25.262409
localtimestamp()        | 2022-07-20 20:15:25.262409
localtime()             | 2022-07-20 20:15:25.262409
sysdate()               | 2022-07-20 20:15:26.468210
sysdate(3)              | 2022-07-20 20:15:26.468000
curdate()               | 2022-07-20
curtime()               | 20:15:26.469603
current_time()          | 20:15:26.469746
current_date()          | 2022-07-20
CURRENT_DATE            | 2022-07-20
CURRENT_TIME            | 20:15:26.469869
CURRENT_TIMESTAMP       | 2022-07-20 20:15:25.262409
LOCALTIME               | 2022-07-20 20:15:25.262409
LOCALTIMESTAMP          | 2022-07-20 20:15:25.262409

PPL

source=calcs | top 1 zzz | eval `now()` = now(), `current_timestamp()` = current_timestamp(), `localtimestamp()` = localtimestamp(), `localtime()` = localtime(), `sysdate()` = sysdate(), `sysdate(3)` = sysdate(3), `curdate()` = curdate(), `curtime()` = curtime(), `current_time()` = current_time(), `current_date()` = current_date(), `CURRENT_DATE` = CURRENT_DATE, `CURRENT_TIME` = CURRENT_TIME, `CURRENT_TIMESTAMP` = CURRENT_TIMESTAMP, `LOCALTIME` = LOCALTIME, `LOCALTIMESTAMP` = LOCALTIMESTAMP;

fetched rows / total rows = 1/1
-[ RECORD 1 ]-------------------------
zzz                     | f
now()                   | 2022-07-20 20:17:22.451338
current_timestamp()     | 2022-07-20 20:17:22.451338
localtimestamp()        | 2022-07-20 20:17:22.451338
localtime()             | 2022-07-20 20:17:22.451338
sysdate()               | 2022-07-20 20:17:22.760505
sysdate(3)              | 2022-07-20 20:17:22.760000
curdate()               | 2022-07-20
curtime()               | 20:17:22.760584
current_time()          | 20:17:22.760626
current_date()          | 2022-07-20
CURRENT_DATE            | 2022-07-20
CURRENT_TIME            | 20:17:22.760693
CURRENT_TIMESTAMP       | 2022-07-20 20:17:22.451338
LOCALTIME               | 2022-07-20 20:17:22.451338
LOCALTIMESTAMP          | 2022-07-20 20:17:22.451338

Implementation details

NOW and SYSDATE difference
According to MySQL standard

NOW() returns a constant time that indicates the time at which the statement began to execute.

SYSDATE() returns the time at which it executes.

I had to save and then to pick time when plugin receives a query. QueryContext was chosen to store this unless a better candidate introduced.

Parser update

1. datetimeConstantLiteral was added to SQL and PPL parsers. It lists pseudo-constants which actually invoke corresponding functions without (). So CURRENT_DATE is shortcut for CURRENT_DATE() and so on.
2. AstExpressionBuilder were updated to call a function when datetimeConstantLiteral met.
3. AstExpressionBuilder in PPL is updated a bit by adding visitFunction method and removing some duplicated code. Copied from AstExpressionBuilder in SQL.
4. ANTLR rules were copied from SQL to PPL.
5. ConstantFunction entity added to represent functions which values should be cached in scope of the current query. Cache is stored in AnalysisContext. This includes changes in:

• SQL parser
• PPL parser
• ExpressionAnalyzer

6. All functions are cached (are ConstantFunction) except:

• sysdate
• curdate
• current_date

7. Since now() and now(int) are different functions, they can't use common cache. To avoid these functions being executed more than once, func(int) signatures of them were removed.

Please see PR Bit-Quill#113 which adds caching mechanism.

Doctests
Doctests for new functions always fail, because test validate exact string match for result. I added docs, but disabled doctests for them.

Issues Resolved

• [FEATURE] Support date and time functions #722
• Support date and time functions CURDATE, MAKETIME, NOW in new engine #93
• Date time query improvement #46
• SQL Plugin returns double instead of date type for functions NOW() and CURDATE() [BUG] #260

See also

• https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html
• Support implicit type conversion from string to temporal #171

Check List

• New functionality includes testing.
  • All tests pass, including unit test, integration test and doctest
• New functionality has been documented.
  • New functionality has javadoc added
  • New functionality has user manual doc added
• Commits are signed per the DCO using --signoff

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[dai-chen]

Thanks for the changes!

[MaxKsyunz]

@Yury-Fridlyand please update the target branch from main to 2.x

[acarbonetto]

nit: should have inserted these alphabetically into the above list

[Yury-Fridlyand]

I'll update in next PR

[dai-chen]

LGTM. Thanks for the changes!