-
Features Support
----------------
-
.. _feature-table:
- | Currently only part of `AWS select command <https://docs.aws.amazon.com/AmazonS3/latest/dev/s3-glacier-select-sql-reference-select.html>`_ is implemented, table bellow describes what is currently supported.
+ | Currently only part of `AWS select command <https://docs.aws.amazon.com/AmazonS3/latest/dev/s3-glacier-select-sql-reference-select.html>`_ is implemented, table below describes what is currently supported.
| The following table describes the current implementation for s3-select functionalities:
+---------------------------------+-----------------+-----------------------------------------------------------------------+
-| Feature | Detailed | Example |
+| Feature | Detailed | Example / Description |
+=================================+=================+=======================================================================+
-| Arithmetic operators | ^ * / + - ( ) | select (int(_1)+int(_2))*int(_9) from stdin; |
+| Arithmetic operators | ^ * % / + - ( ) | select (int(_1)+int(_2))*int(_9) from s3object; |
++---------------------------------+-----------------+-----------------------------------------------------------------------+
+| | ``%`` modulo | select count(*) from s3object where cast(_1 as int)%2 == 0; |
++---------------------------------+-----------------+-----------------------------------------------------------------------+
+| | ``^`` power-of | select cast(2^10 as int) from s3object; |
++---------------------------------+-----------------+-----------------------------------------------------------------------+
+| Compare operators | > < >= <= == != | select _1,_2 from s3object where (int(_1)+int(_3))>int(_5); |
++---------------------------------+-----------------+-----------------------------------------------------------------------+
+| logical operator | AND OR NOT | select count(*) from s3object where not (int(1)>123 and int(_5)<200); |
++---------------------------------+-----------------+-----------------------------------------------------------------------+
+| logical operator | is null | return true/false for null indication in expression |
++---------------------------------+-----------------+-----------------------------------------------------------------------+
+| logical operator | is not null | return true/false for null indication in expression |
++---------------------------------+-----------------+-----------------------------------------------------------------------+
+| logical operator and NULL | unknown state | review null-handle_ observe how logical operator result with null. |
+| | | the following query return **0**. |
+| | | ``select count(*) from s3object where null and (3>2);`` |
++---------------------------------+-----------------+-----------------------------------------------------------------------+
+| Arithmetic operator with NULL | unknown state | review null-handle_ observe the results of binary operations with NULL|
+| | | the following query return **0**. |
+| | | ``select count(*) from s3object where (null+1) and (3>2);`` |
++---------------------------------+-----------------+-----------------------------------------------------------------------+
+| compare with NULL | unknown state | review null-handle_ observe results of compare operations with NULL |
+| | | the following query return **0**. |
+| | | ``select count(*) from s3object where (null*1.5) != 3;`` |
++---------------------------------+-----------------+-----------------------------------------------------------------------+
+| missing column | unknown state | select count(*) from s3object where _1 is null; |
++---------------------------------+-----------------+-----------------------------------------------------------------------+
+| projection column | similar to | select case |
+| | if/then/else | when (1+1==(2+1)*3) then 'case_1' |
+| | | when ((4*3)==(12)) then 'case_2' else 'case_else' end, |
+| | | age*2 from s3object; |
++---------------------------------+-----------------+-----------------------------------------------------------------------+
+| logical operator | ``coalesce`` :: return first non-null argumnet |
+| | select coalesce(nullif(5,5),nullif(1,1.0),age+12) from s3object; |
++---------------------------------+-----------------+-----------------------------------------------------------------------+
+| logical operator | ``nullif`` :: return null in case both arguments are equal, or else the first one |
+| | nullif(1,1)=NULL nullif(null,1)=NULL nullif(2,1)=2 |
+| | select nullif(cast(_1 as int),cast(_2 as int)) from s3object; |
++---------------------------------+-----------------+-----------------------------------------------------------------------+
+| logical operator | ``{expression} in ( .. {expression} ..)`` |
+| | select count(*) from s3object |
+| | where 'ben' in (trim(_5),substring(_1,char_length(_1)-3,3),last_name); |
++---------------------------------+-----------------+-----------------------------------------------------------------------+
+| logical operator | ``{expression} between {expression} and {expression}`` |
+| | select count(*) from stdin |
+| | where substring(_3,char_length(_3),1) between "x" and trim(_1) |
+| | and substring(_3,char_length(_3)-1,1) == ":"; |
+---------------------------------+-----------------+-----------------------------------------------------------------------+
-| | | select ((1+2)*3.14) ^ 2 from stdin; |
+| logical operator | ``{expression} like {match-pattern}`` |
+| | select count(*) from s3object where first_name like '%de_'; |
+| | select count(*) from s3object where _1 like \"%a[r-s]\; |
+---------------------------------+-----------------+-----------------------------------------------------------------------+
-| Compare operators | > < >= <= == != | select _1,_2 from stdin where (int(1)+int(_3))>int(_5); |
+| casting operator | select cast(123 as int)%2 from s3object; |
+---------------------------------+-----------------+-----------------------------------------------------------------------+
-| logical operator | AND OR | select count(*) from stdin where int(1)>123 and int(_5)<200; |
+| casting operator | select cast(123.456 as float)%2 from s3object; |
+---------------------------------+-----------------+-----------------------------------------------------------------------+
-| casting operator | int(expression) | select int(_1),int( 1.2 + 3.4) from stdin; |
+| casting operator | select cast('ABC0-9' as string),cast(substr('ab12cd',3,2) as int)*4 from s3object; |
+---------------------------------+-----------------+-----------------------------------------------------------------------+
-| |float(expression)| select float(1.2) from stdin; |
+| casting operator | select cast(substring('publish on 2007-01-01',12,10) as timestamp) from s3object; |
+---------------------------------+-----------------+-----------------------------------------------------------------------+
-| | timestamp(...) | select timestamp("1999:10:10-12:23:44") from stdin; |
+| non AWS casting operator | select int(_1),int( 1.2 + 3.4) from s3object; |
+---------------------------------+-----------------+-----------------------------------------------------------------------+
-| Aggregation Function | sum | select sum(int(_1)) from stdin; |
+| non AWS casting operator | select float(1.2) from s3object; |
+---------------------------------+-----------------+-----------------------------------------------------------------------+
-| Aggregation Function | min | select min( int(_1) * int(_5) ) from stdin; |
+| not AWS casting operator | select timestamp('1999:10:10-12:23:44') from s3object; |
+---------------------------------+-----------------+-----------------------------------------------------------------------+
-| Aggregation Function | max | select max(float(_1)),min(int(_5)) from stdin; |
+| Aggregation Function | sum | select sum(int(_1)) from s3object; |
+---------------------------------+-----------------+-----------------------------------------------------------------------+
-| Aggregation Function | count | select count(*) from stdin where (int(1)+int(_3))>int(_5); |
+| Aggregation Function | avg | select avg(cast(_1 a float) + cast(_2 as int)) from s3object; |
+---------------------------------+-----------------+-----------------------------------------------------------------------+
-| Timestamp Functions | extract | select count(*) from stdin where |
-| | | extract("year",timestamp(_2)) > 1950 |
-| | | and extract("year",timestamp(_1)) < 1960; |
+| Aggregation Function | min | select min( int(_1) * int(_5) ) from s3object; |
+---------------------------------+-----------------+-----------------------------------------------------------------------+
-| Timestamp Functions | dateadd | select count(0) from stdin where |
-| | | datediff("year",timestamp(_1),dateadd("day",366,timestamp(_1))) == 1; |
+| Aggregation Function | max | select max(float(_1)),min(int(_5)) from s3object; |
+---------------------------------+-----------------+-----------------------------------------------------------------------+
-| Timestamp Functions | datediff | select count(0) from stdin where |
-| | | datediff("month",timestamp(_1),timestamp(_2))) == 2; |
+| Aggregation Function | count | select count(*) from s3object where (int(1)+int(_3))>int(_5); |
+---------------------------------+-----------------+-----------------------------------------------------------------------+
-| Timestamp Functions | utcnow | select count(0) from stdin where |
-| | | datediff("hours",utcnow(),dateadd("day",1,utcnow())) == 24 ; |
+| Timestamp Functions | extract | select count(*) from s3object where |
+| | | extract('year',timestamp(_2)) > 1950 |
+| | | and extract('year',timestamp(_1)) < 1960; |
+---------------------------------+-----------------+-----------------------------------------------------------------------+
-| String Functions | substr | select count(0) from stdin where |
-| | | int(substr(_1,1,4))>1950 and int(substr(_1,1,4))<1960; |
+| Timestamp Functions | dateadd | select count(0) from s3object where |
+| | | datediff('year',timestamp(_1),dateadd('day',366,timestamp(_1))) == 1; |
++---------------------------------+-----------------+-----------------------------------------------------------------------+
+| Timestamp Functions | datediff | select count(0) from s3object where |
+| | | datediff('month',timestamp(_1),timestamp(_2))) == 2; |
++---------------------------------+-----------------+-----------------------------------------------------------------------+
+| Timestamp Functions | utcnow | select count(0) from s3object where |
+| | | datediff('hours',utcnow(),dateadd('day',1,utcnow())) == 24 ; |
++---------------------------------+-----------------+-----------------------------------------------------------------------+
+| String Functions | substring | select count(0) from s3object where |
+| | | int(substring(_1,1,4))>1950 and int(substring(_1,1,4))<1960; |
++---------------------------------+-----------------+-----------------------------------------------------------------------+
+| String Functions | trim | select trim(' foobar ') from s3object; |
++---------------------------------+-----------------+-----------------------------------------------------------------------+
+| String Functions | trim | select trim(trailing from ' foobar ') from s3object; |
++---------------------------------+-----------------+-----------------------------------------------------------------------+
+| String Functions | trim | select trim(leading from ' foobar ') from s3object; |
++---------------------------------+-----------------+-----------------------------------------------------------------------+
+| String Functions | trim | select trim(both '12' from '1112211foobar22211122') from s3objects; |
++---------------------------------+-----------------+-----------------------------------------------------------------------+
+| String Functions | lower/upper | select lower('ABcD12#$e') from s3object; |
++---------------------------------+-----------------+-----------------------------------------------------------------------+
+| String Functions | char_length | select count(*) from s3object where char_length(_3)==3; |
+| | character_length| |
++---------------------------------+-----------------+-----------------------------------------------------------------------+
+| Complex queries | select sum(cast(_1 as int)), |
+| | max(cast(_3 as int)), |
+| | substring('abcdefghijklm', |
+| | (2-1)*3+sum(cast(_1 as int))/sum(cast(_1 as int))+1, |
+| | (count() + count(0))/count(0)) from s3object; |
+---------------------------------+-----------------+-----------------------------------------------------------------------+
| alias support | | select int(_1) as a1, int(_2) as a2 , (a1+a2) as a3 |
-| | | from stdin where a3>100 and a3<300; |
+| | | from s3object where a3>100 and a3<300; |
+---------------------------------+-----------------+-----------------------------------------------------------------------+
+.. _null-handle:
+
+NULL
+~~~~
+| NULL is a legit value in ceph-s3select systems similar to other DB systems, i.e. systems needs to handle the case where a value is NULL.
+| The definition of NULL in our context, is missing/unknown, in that sense **NULL can not produce a value on ANY arithmetic operations** ( a + NULL will produce NULL value).
+| The Same is with arithmetic comaprision, **any comparison to NULL is NULL**, i.e. unknown.
+| Below is a truth table contains the NULL use-case.
+
++---------------------------------+-----------------------------+
+| A is NULL | Result (NULL=UNKNOWN) |
++=================================+=============================+
+| NOT A | NULL |
++---------------------------------+-----------------------------+
+| A OR False | NULL |
++---------------------------------+-----------------------------+
+| A OR True | True |
++---------------------------------+-----------------------------+
+| A OR A | NULL |
++---------------------------------+-----------------------------+
+| A AND False | False |
++---------------------------------+-----------------------------+
+| A AND True | NULL |
++---------------------------------+-----------------------------+
+| A and A | NULL |
++---------------------------------+-----------------------------+
+
s3-select function interfaces
-----------------------------
| ``datediff(date-part,timestamp,timestamp)`` : function return an integer, a calculated result for difference between 2 timestamps according to date-part.
| supported date-part : year,month,day,hours.
-
| ``utcnow()`` : return timestamp of current time.
Aggregation functions
| ``sum(expression)`` : return a summary of expression per all rows matching condition(if such exist).
+ | ``avg(expression)`` : return a average of expression per all rows matching condition(if such exist).
+
| ``max(expression)`` : return the maximal result for all expressions matching condition(if such exist).
| ``min(expression)`` : return the minimal result for all expressions matching condition(if such exist).
String functions
~~~~~~~~~~~~~~~~
- | ``substr(string,from,to)`` : return a string extract from input string according to from,to inputs.
+ | ``substring(string,from,to)`` : return a string extract from input string according to from,to inputs.
+
+ | ``char_length`` : return a number of characters in string (``character_length`` does the same).
+
+ | ``trim`` : trims leading/trailing characters from target string, the default is blank character.
+
+ | ``upper\lower`` : converts characters into lowercase/uppercase.
Alias
| Sending s3-select request to RGW using AWS cli, should follow `AWS command reference <https://docs.aws.amazon.com/cli/latest/reference/s3api/select-object-content.html>`_.
- | bellow is an example for it.
+ | below is an example for it.
::
'{"CSV": {"FieldDelimiter": "," , "QuoteCharacter": "\"" , "RecordDelimiter" : "\n" , "QuoteEscapeCharacter" : "\\" , "FileHeaderInfo": "USE" }, "CompressionType": "NONE"}'
--output-serialization '{"CSV": {}}'
--key {OBJECT-NAME}
- --expression "select count(0) from stdin where int(_1)<10;" output.csv
+ --expression "select count(0) from s3object where int(_1)<10;" output.csv
Syntax
~~~~~~
run_s3select(
"my_bucket",
"my_csv_object",
- "select int(_1) as a1, int(_2) as a2 , (a1+a2) as a3 from stdin where a3>100 and a3<300;")
+ "select int(_1) as a1, int(_2) as a2 , (a1+a2) as a3 from s3object where a3>100 and a3<300;")
projects / ceph.git / commitdiff