cursor()

Read(5941) Label: cursor,

Here’s how to use cursor() function.

cursor()

Description:

 Call a cellset file and return the result set returned from the execution of the file as a cursor.

Syntax:

cursor(dfx,…)

Note:

The function calls a cellset file and returns the result set returned from the execution of the file as a cursor. When there are multiple return statements in the dfx file, first merge the result sets returned by the return statements, and then return the merge result as a cursor. These result sets of return must be of the same structure, or error will be reported. Use either an absolute path or a relative path to search for the dfx file. With the relative path, the search order is Class path –> Search path –> Main directory. The cursor the function returns is irreversible.

Parameter:

dfx

Cellset file name

dfx’s parameter

Option:

@c

The dfx can be represented by a cell that corresponds to a subroutine defined by func() function

Return value:

Cursor

Example:

Here’s test.dfx cellset file under the main directory in which arg1 is the cellset parameter:

 

A

B

 

1

for arg1

 

 

2

 

=connect("demo").query("select * from GYMNASTICSWOMEN where ID=?",A1)

 

3

 

=B2.derive(avg(VAULT,UNEVENBARS,BALANCEBEAM,FLOOR):Average)

 

4

 

return B3

Perform a loop computation and return the result sets.

 

 

A

 

1

=[5,10,20,25]

 

 

2

=cursor("test.dfx",A1)

Cll test.dfx, pass A1’s sequence as the value of parameter arg1, and return result as a cursor.

3

=A2.fetch()

Fetch records from the cursor; the result is the union of returned result sets by the loop computation of test.dfx.

4

=call("test.dfx",A1)

Use call function to call test.dfx but only the result set of the first loop is returned. 

 

 

A

B

 

1

func

 

 

2

 

return A1.sum()

 

3

=cursor@c(A1,[2,5,7])

 

Call the code block whose master cell is A1.

4

=A3.fetch()

 

14.

cursor cs cursor … cursor

Description:

Define a channel for each cursor according to a specified cursor.

Syntax:

cursor cs

cursor

cursor

Note:

The statement defines a channel for each cursor according to cursor cs (the value of the cursor cell is a channel), traverses cs to perform a calculation over the channel in the code block and write the result into the cell of cursor.

Parameter:

cs

A cursor

A code block

Return value:

Result set of channel

Example:

 

A

B

 

1

=to(100000).new(rand(1000):f1,rand(1000):f2).cursor()

 

Generate a cursor.

2

cursor A1

=A2.groups(f1:count(1))

Traverse cursor A1, calculate A2’s channel in B2’s code block and write the result to A2.

3

cursor

=A3.groups(f2:count(1))

Same as the above.

A.cursor()

Description:

Generate a cursor from a sequence.

Syntax:

A.cursor(k:n)

Note:

The function generates a cursor based on sequence A, divides the cursor data into n segments, and retrieves the kth segment.

Parameter:

A

A sequence

k

Segment number

n

The number of data segments; retrieve all data out when both k and n are omitted

Option:

@p

Assume data is ordered by the first field and the division won’t put records having same first field to different segments

Return value:

Cursor

Example:

 

A

 

1

=demo.query("select * from SCORES")

Return a sequence.

2

=A1.cursor(1:3)

Generate a cursor using A1’s sequence, divide the cursor into three segments, and retrieve the 1st segment to return.

3

=A1.cursor()

Generate a cursor using A1’s sequence; return all data of the cursor when parameters are absent.

4

=demo.query("select  CLASS,STUDENTID,SUBJECT,SCORE from SCORES").sort(CLASS)

Return a sequence ordered by the 1st field.

5

=A4.cursor@p(1:3)

With @p option, put records having same Class value in one segment, during which records are not allocated strictly according to parameters k and n.

A.cursor@m(n)

Description:

Generate a multicursor from a sequence.

Syntax:

A.cursor@m(n)

Note:

The function generates a multicursor using sequence A.

Parameter:

A

A sequence

n

Number of subcursors; by default the value isDefault subcursor count in a multicursorconfigured in the designer; when integrating esProc in a third-party application, its default value is cursorParallelNum value configured in raqsoftConfig.xml file

Option:

@p

Assume the sequence is ordered by the 1st field and records having same 1st field value won’t be put into two segments

Return value:

Multicursor

Example:

 

A

 

1

=demo.query("select  CLASS,STUDENTID,SUBJECT,SCORE  from SCORES")

Return a sequence.

2

=A1.cursor@m()

Generate a multicursor from A1’s sequence; as parameters are absent, use value ofDefault subcursor count in a multicursoras the default number of subcursors.

3

=demo.query("select  CLASS,STUDENTID,SUBJECT,SCORE  from SCORES").sort(CLASS)

Return a sequence ordered by the 1st field.

4

=A1.cursor@mp(3)

Generate a multicursor having three subcursors; with @p option, the segmentation won’t put records having same CLASS value in two segments.

A.cursor@m(mcs,K:K’,...)

Description:

Generate a multicursor segmented synchronously as an existing multicursor using a specified sequence.

Syntax:

A.cursor@m(mcs,K:K‘,...)

Note:

The function divides ordered sequence A into multiple segments according to multicursor mcs and returns a multicursor. Parameters K and K’ are segmentation keys of A and mcs respectively.

Parameter:

A

An ordered sequence

mcs

A multicursor

K

A’s segmentation key

K’

mcs’s segmentation key

Option:

@p

Ignore parameters K and K’ and divide ordered sequence A by comparing and matching the first fields of mcs and A

Return value:

Multicursor

Example:

 

A

 

1

=to(10000).new(#:c1,rand():c2).sort(c1)

Generate a sequence.

2

=A1.cursor@m(3)

Generate a multicursor having three subcursors from A1’s table sequence.

3

=to(10000).new(#:k1,rand(10000):k2,rand()*1000:k3).sort(k1)

Generate a table sequence ordered by k1.

4

=A3.cursor@m(A2,k1:c1)

Generate a multicursor segmented synchronously as A2’s multicursor, whose segmentation key is c1, based on A3’s table sequence, whose segmentation key is k1.

5

=A3.cursor@mp(A2)

Generate a multicursor segmented synchronously as A2’s multicursorbased on A3’s table sequence; as @p option is present, perform the segmentation by comparing and matching the first fields of A3 and A2, and in this case segmentation key parameters are not needed in the expression.

db.cursor()

Description:

Create a database cursor by executing an SQL statement.

Syntax:

db. cursor(sql {,args …})

Note:

The function creates a database cursor by executing SQL. The cursor will be automatically closed after a full data scan.

Parameter:

db

Database connection

sql

A SQL query statement

args

Parameters passed to SQL, which can be values or names defined; separate multiple parameters with comma

 

Option:

@i

If the result set has only one column, the content of the returned cursor is a sequence

@d

Convert the numeric data type to the double data type, instead of the decimal data type

@x

Disconnect from the database automatically when the cursor is closed; this option applies to connect -mode database connection only; with this option, the cursor the function returns is irreversible

@v

Generate a cursor of pure table sequence or pure sequence

Return value:

A cursor

Example:

 

A

 

1

=demo.cursor("select * from SCORES")

Parameter db is data source name; this requires that demo data source is already connected.

2

=connect("demo")

 

3

=A2.cursor@x("select * from SCORES").fetch()

With connect-mode database connection, @x is used.

4

=A2.cursor("select * from STUDENTS")

Error is reported: Data Source demo is shutdown or wrong setup., which prompts you that data source isn’t started as database is automatically disconnected when A3’s cursor is closed.

When the SQL query statement contains parameters:

 

A

 

1

>arg2="R&D"

Define parameter name as arg2 and parameter value as "R&D".

2

=demo.cursor("select EID,NAME,DEPT,GENDER from employee  where  EID<? and DEPT=?  and  GENDER=?",arg1,arg2,"M")

Query employee table, where arg1 is a cellset parameter whose value is 100 and arg2 is a parameter defined in A1, and the 3rd parameter receives value “M” directly.

3

=A2.fetch()

Fetch data from A2’s cursor.

Return cursor containing other types of data:

 

A

 

1

=demo.cursor("select NAME from  STUDENTS")

Query NAME field of STUDENTS table from demo data source and return a cursor whose content is as follows:

2

=demo.cursor@i("select  NAME from  STUDENTS")

When the result set contains only one column, use @i option to return content of the cursor as a sequence.

3

=demo.cursor@v("select * from  STUDENTS")

Return a cursor of pure table sequence.

4

=demo.cursor@iv("select  NAME from  STUDENTS")

Return a cursor of pure sequence.

5

=mysql.cursor@d("select * from ta")

As @d option is present, numeric data is converted to double type.

Related function:

cs.fetch()

cs.skip()

f.cursor()

Description:

Create a cursor based on a file.

Syntax:

f.cursor()

f.cursor(Fi:type,…; k:n,s)

Note:

The function creates a cursor based on file f and returns it. The cursor will be automatically closed after a full data scan.

Parameter:

f

File object, only supporting the textual file object

Fi

Fields to be retrieved; all fields will be retrieved by default. The to-be-retrieved field(s) can be represented by their ordinal numbers headed by the sign #

type

Field types, including bool, int, long, float, decimal, string, date, time and datetime. Data type of the first row will be used by default

s

User-defined separator. The default is tab. When the parameter is omitted, the comma preceding it can be omitted, too

k

The segment number

n

The number of segments. Retrieve the whole file when both k and n are omitted

Option:

@t

Use the first row of f as the field names. If omitted, use_1,_2,… as the default field names

@b

Retrieve data from a binary file written in the method of export, with the support of parameters Fi, k and n, and without support of parameters type and s. Ignore options @t, @s, @i and @q. The segmental retrieval could result in empty segment in cases when a file has only a very small number of records

@e

Make the function return null when Fi doesn’t exist in the file; raise an error when the option is absent 

@x

Delete the source file automatically on closing the cursor; the cursor that the function returns is irreversible when this option works

@s

Not split the to-be-retrieved field when it is imported as a cursor whose content is a table sequence consisting of strings of a single field; in this case the parameters will be ignored.

@i

If the result set has only one column, the content of the returned cursor will be a sequence.

@q

Remove the quotation marks, if any, from the field strings, including the field names, in the first place, and handle escape sequences

@c

Use comma as the separator when parameter s is absent

@m

With the option, the f.cursor@m(Fi:type,…;n,s) function returns a multicursor;  here parameter n is the number of segments; use the value of Default subcursor count in a multicursordefined in the designer as the number subcursors if the option is absent; when integrating esProc into a third-party application, use cursorParallelNum value configured in raqsoftConfig.xml file as the default

@o

Use quotation marks as the escape character

@k

Retain the white space on both sides of the data item; without it a trim operation will be automatically performed

@d

Delete a record if it contains unmatching data types or data formats and start examining data by type, or if the parentheses and the quotation marks in it do not match when @p option and @q option respectively are present

@n

Ignore and discard rows whose number of columns don’t match the first row

@v

 

Throw an exception, terminate the execution and output the content of the problem record when errors appear in @d check and @n check

@w

Read each row, including the column headers row, as a sequence and return a cursor of sequence made up of sequences

@a

Treat single quotes as quotes, including scenarios where the option cooperates with @q option; single quotes are left not handled when both options are absent

@p

Enable handling the matching of parentheses (not including the separators within the parentheses) and quotes, as well as the escape sequences outside of the quotes

@f

Split the file content into a string by the separator without parsing

@l

Allow line continuation if there is an escape character \ at the end of the line

Return value:

Cursor/Multicursor

Example:

 

A

B

C

 

1

=file("D://Student.txt").cursor@tx()

 

 

Return the cursor for retrieving data, take the record in the first row as field names, and delete the file automatically when closing the cursor.

2

=create(CLASS,STUDENTID,SUBJECT,SCORE)

 

 

Construct a new table sequence.

3

for

 

 

 

4

 

if A3==1

=A1.skip(5)

If the loop number is 1, then skip 5 consecutive rows.

5

 

=A1.fetch(3)

 

Retrieve data from cursorA1, 3 rows each time.

6

 

if B5==null

 

Jump out from the loop when B5 is null.

7

 

 

Break

 

8

 

else

 

 

9

 

 

>A2.insert(0:B5,CLASS,STUDENTID,SUBJECT,SCORE)

Insert records in B5 into A2.

10

=file("D://Department.txt").cursor@t(Dept,Manager;,"/")

 

=A10.fetch()

Below is Department.txt:

Contents of Department. txt are separated with the slashes and read out according to the specified fields of DEPT and MANAGER.

11

=file("D://Department5.txt").cursor@t(;1:2)

 

=A11.fetch()

With Fi and s omitted, the function separates the cursor into 2 segments and retrieves the first one.

12

=file("D:// EMPLOYEE. btx").cursor@b(GENDER;1:2)

 

=A12.fetch()

Retrieve the GENDER field of the bin file, EMPLOYEE.btx(a segmented binary file) exported through f.export@z(); by default the exported binary file includes field names.

13

=file("D://EMPLOYEE.btx").cursor@b(;1:2)

 

=A13.fetch()

Retrieve the segmented binary file, EMPLOYEE1.btx, exported by f.export@b(), divide the file contents into 2 parts, and get the first part.

14

=file("D://Department.txt").cursor@ts()

 

= A14.fetch()

Won’t split fields, the cursor contains a table sequence consisting of a single string field.

15

=file("D://StuName.txt").cursor@i()

 

=A15.fetch()

StuName.txt is a file containing only one field, so the content of the cursor is a sequence.

16

=file("D://EMPLOYEE1.txt").cursor@tc()

 

=A16.fetch()

Retrieve the first segment of GENDER field of comma-seperated EMPLOYEE1.txt.

17

=file("D://Department3.txt").cursor@e(EID)

 

=A17.fetch()

Return null since EID field can’t be found in Department3.txt; without @e option, error will be reported, saying EID: field is not found.

18

=file("D://Department2.txt").cursor@tq(;,"|")

 

=A18.fetch()

Below is Department2.txt:  

B19’s result:

19

=file("D://Department.txt").cursor@tm(DEPT:string,MANAGER:int;3,"/")

 

 

The cursor is devided into 3 segments and the result of A19 is returned as a multicursor.

20

=file("D://Sale1.txt").cursor(#1,#3)

 

=A20.fetch()

Below is the Sale1.txt file:

 

Below is the result of B20:

21

=file("D:/Dep3.txt").cursor@cqo()

 

=A21.fetch()

Here is the Dep3.txt file:

With @o option, two double quotation marks are treated as one and return the result as follows:

22

=file("D:/Dep1.txt").cursor@k()

 

=A22.fetch()

Retain the whitespace characters on both sides of the data item.

 

23

=file("D:/Department1.txt").cursor@t(id:int,name;,"|")

 

=A23.fetch()

Return id and name fields of Department1.txt.

24

=file("D:/Department1.txt").cursor@td(id:int,name;,"|")

 

=A24.fetch()

Delete a record containing unmatching data types; rows where id value is a are deleted.

25

=file("D:/Department1.txt").cursor@tv(id:int,name;,"|")

 

=A25.fetch()

Verify data type matching, and, and if error reports, throw an exception, terminate the execution and output the content of the problem record; data type doesn’t match with rows where id value is a.

 

26

=file("D:/Dep2.txt").cursor@tdn(id:int,name,surname;,"|")

 

=A26.fetch()

Here’s the file Dep2.txt:

Ignore row 6 and row 8 because the number of columns doesn’t match that in row 1.

27

=file("D:/Desktop/DemoData/txt/City.txt").cursor@w()

 

=A27.fetch()

Use @w option to read each row as a sequence and return a cursor of sequence whose members are sequences.

28

=file("D://t1.txt").cursor@c()

 

=A28.fetch()

Below is t1.txt:

With @c option, use the comma as the default separator and return result as follows:

29

=file("D://t1.txt").cursor@cp()

 

=A29.fetch()

With @p option, parentheses and quotation marks matching will be handled during parsing.

30

=file("D://t1.txt").cursor@cpa()

 

=A30.fetch()

With @a option, single quotes are treated as quotes.

31

=file("D://t2.txt").cursor@l()

 

=A31.fetch()

Below is t2.txt:

With @1 option, allow line continuation when there is an escape character at the end of the line.

32

=file("D://t3.txt").cursor@f()

 

=A32.fetch()

With @f option, just splt the file as a string using the separator.

Related functions:

cs.fetch()

cs.skip()

db.cursor()

T.cursor(x:C,…;wi…;k:n)

Description:

Segment an entity table or an in-memory table or a multizone composite table and return the cursor of a specified segment.

Syntax:

T.cursor(x:C,…;wi,…;k:n)

Note:

The function computes expression x over data in entity table/in-memory table/multizone composite table T, filters the result table according to filtering expression wi, splits it into n segment and returns the kth segment as a cursor, where C is the field name. If T is an attached table, the queried data is allowed to include a primary table field.

 

Segment all zone tables synchronously and merge the result when T is a multizone composite table. The process is like this: split zone table 1 into n segments, divide each of the other zone tables synchronously according to the zone table 1, retreive the kth segment of each zone table, and merge them by the dimension and return the result.

Option:

@m

The T.cursor@m(x:C…;wi,...;n) function with this option generates a multicursor segmented into n parts. n is an integer; the function returns an ordinary cursor if n<2; use the value ofDefault number of subcursors in a multicursor set inTool-Optionsif n is absent

@v

Generate a pure table sequence-based column-wise cursor, which has higher performance than regular cursors

@x

Automatically close the entity table/in-memory table after data in the cursor is fetched

@o

Get records in order without merging zone tables when T is a multizone composite table; all zone tables are segmented synchronously

@w

Used on a multizone composite table;

Perform update merge; when zone tables share a same key value, ignore the record contained in the zone table with a smaller number; segmentation is performed according to the way zone table 1 is split; retrieve a zone table after the first one wholly if they are small enough;

Handle the deletion mark and do not return records with a deletion mark to the cursor; but if the key value of a record with the deletion mark is unique in the multizone composite table, just retain it;

This option enables retrieving key field(s) as well as the deletion mark field, if there is one, forcefully

@z

Get data in the inverse order; do not support segmentation in this case

Parameter:

T

An entity table or an in-memory table or a multizone composite table

x

Expression; by default all fields of T will be returned to the cursor

C

Column alias; can be omitted

wi

Filtering condition; separate multiple conditions by comma(s) and their relationships are AND; besides regular filtering expressions, you can also use the following five types of syntax in a filtering condition, where K is a field in the entity table:

1K=w

w usually uses expression Ti.find(K) or Ti.pfind(K), where Ti is a table sequence. When value of w is null or false, the corresponding record in the entity table will be filtered away; when w is expression Ti.find(K) and the to-be-selected fields C,... contain K, Ti’s referencing field will be assigned to K; when w is expression Ti.pfind(K) and the to-be-selected fields C,... contain K, ordinal numbers of K values in Ti will be assigned to K.

2(K1=w1,Ki=wi,w)

Ki=wi is an assignment expression. Generally, parameter wi can use expression Ti.find(Ki) or Ti.pfind(K), where Ti is a table sequence; when wi is expression Ti.find(K) and the to-be-selected fields C,... contain Ki, Ti’s referencing field will be assigned to Ki correspondingly; when wi is expression Ti.pfind(Ki) and the to-be-selected fields C,... contain Ki, ordinal numbers of Ki values in Ti will be assigned to Ki.

w is a filter expression; you can reference Ki in w.

3K:Ti

Ti is a table sequence. Compare Ki value in the entity table with key values of Ti and discard records whose Ki value does not match; when the to-be-selected fields C,... contain K, Ti’s referencing field will be assigned to K.

4K:Ti:null

Filter away all records that satisfy K:Ti.

5K:Ti:#

Locate records according to ordinal numbers, compare ordinal numbers of records in table sequence Ti according to the entity table’s K values, and discard non-matching records; when the to-be-selected fields C,... contain K, Ti’s referencing field will be assigned to K

k

A positive integer (kn) representing the kth segment

n

A positive integer representing the number of segments; return all records when parameters k:n are absent

Return value:

A unicursor/multicursor

Example:

 

A

 

1

for 100

 

2

=to(10000).new(#:k1,rand():c1).sort@o(k1)

Return a table sequence:

3

=to(10000).new(#:k1,rand(10000):c2,rand()*1000:c3).sort@o(k1)

Return a table sequence:

4

=A2.cursor()

Return a cursor.

5

=A3.cursor()

Return a cursor.

6

=file("D:\\tb4.ctx")

Generate a composite table file.

7

=A6.create(#k1,c1)

Create A6’s base table whose key is k1.

8

=A7.append(A4)

Append data of A4’s cursor to A7’s base table.

9

=A7.attach(table4,c2,c3)

Create an attached table table4 for the base table.

10

=A9.append(A5)

Append data of A5’s cursor to attached table table4.

11

=A9.cursor(;c2<1000;2:3)

Divide records meeting c2<1000 in the attached table into 3 segments and return a cursor of all columns of the second segment.

12

=A11.fetch()

Fetch data from A11’s cursor.

13

=A7.cursor(;c1>0.99)

Get records meeting c1>0.99 from A7’s base table

14

=A13.fetch()

Fetch data from A13’s cursor.

b

15

=A9.cursor(k1,c1:b,c3;c3>999)

Get the base table’s k1 field and c1 field from attached table table4, as well as c3 field of the attached table, according to condition c3>999, and rename c1 b.

16

=A15.fetch()

Fetch data from A15’s cursor.

17

=A9.cursor@m(;;3)

Use @m option to generate a multicursor from attached table table4.

 

 

A

 

1

=file("employee1.ctx")

Generate composite table file employee1.ctx.

2

=A1.create@y(#EID,NAME,GENDER,SALARY)

Create the base table of composite table employee1.ctx, which contains columns EID, NAME, GENDER and SALARY and where EID is the dimension.

3

=connect("demo").cursor("select  EID,NAME,GENDER,SALARY  from  employee")

Return a cursor.

4

=A2.append@i(A3)

Append records of A3’s cursor to A2’s base table.

5

=A2.cursor@v(;SALARY>1000;)

Return a column-wise cursor, and automatically close A2’s composite table after data is fetched from it.

6

=A5.groups(GENDER;avg(SALARY):SALARY_AVG)

Perform grouping & aggregation operation on A5’s cursor.

7

=A2.cursor(;SALARY>2000)

Error is reported, promptingStream Closed .

When T is a multizone composite table:

 

A

 

1

=100000.new(~:ID,rand(2):FM).cursor()

 

2

=file("nc.ctx":[1,2])

Generate a homo-names files group.

3

=A2.create@y(#ID,FM;if(FM==1,1,2))

Return a multizone composite table.

4

=A3.append@x(A1)

Append cursor A1’s data to the multizone composite table; below is content of the multizone composite table:

1.nc.ctx  2.nc.ctx

 

5

=A3.cursor(;;1:3)

Split the multizone composite table into three segments, return the first segment of each zone table, merge them and return result as a cursor:

Data in zone table 1 and that in zone table 2 has been merged by their dimensions.

6

=A3.cursor@o(;;1:3)

With @o option, do not perform merge on the multizone composite table but retrieve records in the order of segments instead; below is the content of the returned cursor:

The upper half of the table is records of zone table 1.nc.ctx and the lower half contains records of 2.nc.ctx.

Use special types of filtering conditions:

 

A

 

1

=file("emp.ctx")

 

2

=A1.open()

Open the composite table file.

3

=A2.import()

As no parameters are present, return all data in the entity table.

4

=5.new(~:ID,~*~:Num).keys(ID)

Generate a table sequence using ID as the key.

5

=A2.cursor(EID,NAME;EID=A4.find(EID))

Use K=w filtering mode; in this case w is Ti.find(K) and entity table records making EID=A4.find(EID) get null or false are discarded; EID is the selected field, to which table sequence A4’s referencing field are assigned.

6

=A2.cursor(EID,NAME;EID=A4.pfind(EID))

Use K=w filtering mode; in this case w is Ti.pfind(K) and entity table records making EID=A4.pfind(EID) get null or false are discarded; EID is the selected field, to which its ordinal numbers in table sequence A4 is assigned.

7

=A2.cursor(EID,NAME;EID:A4)

Use K:Ti filtering mode; compare the entity table’s EID values with the table sequence’s key values and discard entity table records that cannot match.

8

=A2.cursor(NAME,SALARY;EID:A4)

This is a case where K isn’t selected; EID isn’t the selected field, so only filtering is performed.

9

=A2.cursor(EID,NAME;EID:A4:null)

Use K:Ti:null filtering mode; compare the entity table’s EID values with the table sequence’s key values and discard entity table records that can match.

10

=A2.cursor(EID,NAME;EID:A4:#)

Use K:Ti:# filtering mode; compare with ordinal numbers of table sequence’s records according to the entity table’s EID values, and discard records that cannot match.

11

=connect("demo").query("select top 2  NAME,GENDER  from employee").keys(NAME)

Return a table sequence using NAME as the key.

12

=A2.cursor(EID,NAME;(EID=A4.find(EID),NAME=A11.find(NAME),EID!=null&&NAME!=null))

Use (K1=w1,Ki=wi,w) filtring mode; return records that meet all conditions

Use @z option to get data in the inverse order:

 

A

 

1

=100000.new(~:ID,rand(2):FM)

 

2

=file("curz.ctx")

 

3

=A2.create@y(#ID,FM)

Create a composite table.

4

=A3.append@i(A1)

 

5

=A4.cursor().fetch()

Return the composite table as a cursor and fetch data from the cursor:

6

=A4.cursor@z().fetch()

Use @z option to get data in the inverse order and fetch data from the cursor as follows:

Use @w option to perform update merge:

 

A

 

1

=connect("demo").cursor("select  EID,NAME,GENDER  from employee") 

Return a cursor whose content is as follows:

2

=file("ec.ctx":[1,2])

Homo-name files group: 1.ec.ctx and 2.ec.ctx.

3

=A2.create@y(#EID,NAME,GENDER;if(GENDER=="F",1,2))

Create a multizone composite table, set EID as its key and put records where GENDER is F to 1.ec.ctx and the other records to 2.ec.ctx.

4

=A3.append@ix(A1)

Append cursor A1’s data to the multizone composite table.

5

=create(EID,NAME,GENDER).record([1,"AAA","M"]).cursor()

Return a cursor whose content is as follows:

6

=file("ec.ctx":[3])

 

7

=A6.create@y(#EID,NAME,GENDER;3)

Add a zone table named 3.ec.ctx.

8

=A7.append@i(A5)

Append cursor A5’s data to zone table 3.ec.ctx; both zone table 1.ec.ctx and zone table 3.ec.ctx contain records whose primary key values are [1] .

9

=file("ec.ctx":[1,2,3]).open()

Open multizone composite table ec.ctx.

10

=A9.cursor(;;1:3)

Split the multizone composite table into multiple segments, retrieve the first segment and return a cursor, whose content is as follows:

11

=A9.cursor@w(;;1:3)

With @w option, perform update merge and return a cursor whose content is as follows:

Use @w option to recognize deletion mark:

 

A

 

1

=connect("demo").cursor("select  EID,NAME,GENDER  from employee") 

 

2

=A1.derive(false:Defiled)

 

3

=A2.new(EID,Defiled,NAME,GENDER)

Return a cursor whose content is as follows:

4

=file("ecd.ctx":[1,2])

Define a homo-name files group: 1.ecd.ctx and 2.ecd.ctx.

5

=A4.create@yd(#EID,Defiled,NAME,GENDER;if(GENDER=="F",1,2))

Create a multizone composite table, set EID as the key, use @d option to make Defiled field the deletion mark and put records where GENDER is F to 1.ed.ctx and the other records to 2.ed.ctx.

6

=A5.append@ix(A3)

Append cursor A3’s data to the multizone composite table.

7

=create(EID,Defiled,NAME,GENDER).record([2,true,,,0,true,,]).cursor()

Return a cursor whose content is as follows:

8

=file("ecd.ctx":[3])

 

9

=A8.create@yd(#EID,Defiled,NAME,GENDER;3)

Add zone table 3.ecd.ctx and make Defiled the deletion mark field.

10

=A9.append@i(A7)

Append cursor A1’s records to zone table 3.ecd.ctx, where the deletion mark field value corresponding to the record whose primary key value is 2 is true and the record whose primary key value is 0 is a newly-added one in the zone table – which means the latter’s key value is unique.

11

=file("ecd.ctx":[1,2,3]).open()

Open composite table file ecd.ctx.

12

=A11.cursor().fetch()

Return all data in the multizone composite table ecd.ctx to the cursor; below is the returned content:

13

=A11.cursor@w().fetch()

With @w option, return data in composite table ecd.ctx as a cursor and recognize the deletion mark – that is, do not return the record whose primary key value is 2 to the cursor, and retain the record whose value is unique and marked by deletion mark – that is, the record whose primary key value is 0 is returned to the cursor, whose content is as follows:

T.cursor(x,…;wi,...)

Description:

Return the specified column(s) in a cluster entity table/cluster in-memory table as a cluster cursor.

Syntax:

T.cursor(x,…;wi,...)

Note:

The function computes data in a cluster entity table/cluster in-memory table with expression x and the filtering condition w and returns the results as a cluster cursor.

Option:

@m

The function with this option generates a cluster multicursor synchronously segmented into n parts. n is a positive integer representing the number of segments to be divided; the function returns an ordinary cursor if n<2; use the value ofDefault number of subcursors in a multicursorset inTool-Optionsif n is absent

Parameter:

T

A cluster entity table/cluster in-memory table; cannot be a duplicate table

x

An expression

wi

Filtering condition; multiple conditions are separated by comma(s) and their relationships are AND

Return value:

A cluster (multi)cursor

Example:

 

A

 

1

=file(“D:/tb4.ctx”:[1],“169.254.121.62:8281”)

Open a cluster table file.

2

=A1.open()

Return a cluster composite table.

3

=A2.attach(table3)

Retrieve cluster entity table table3.

4

=A2.cursor()

Return a cluster cursor.

5

=A3.cursor(NAME,GENDER;EID<6)

Return NAME field and GENER field where EID<6 as a cluster cursor.

6

=file(“tb5.ctx”:[2],“192.168.31.72:8281”)

 

7

=A6.open()

 

8

=A7.cursor@m(;;3)

Generate a cluster multicursor that is segmented into 3 parts.

9

=A7.cursor()

 

10

=A9.memory()

Generate a cluster in-memory table.

11

=A10.cursor()

Return a cluster cursor.

T.cursor(x:C,…;wi,...;mcs)

Description:

Synchronously segment an entity table/in-memory table/multizone composite table according to a multicursor and return a multicursor.

Syntax:

T.cursor(x:C,…;wi,...;mcs)

Note:

The function synchronously segments entity table/in-memory table/multizone composite table T according to multicursor mcs, during which T’s first field and mcs’s first field will be matched, and returns a multicursor. When T is a multizone composite table, merge zone tables by their dimensions.

Parameter:

T

An entity table/in-memory table/multizone composite table

x

Expression

C

Column alias

wi

Filtering condition; retrieve the whole set when this parameter is absent; separate multiple conditions by comma(s) and their relationships are AND. Besides regular filtering expressions, you can also use the following five types of syntax in a filtering condition, where K is a field in the entity table:

1K=w

w usually uses expression Ti.find(K) or Ti.pfind(K), where Ti is a table sequence. When value of w is null or false, the corresponding record in the entity table will be filtered away; when w is expression Ti.find(K) and the to-be-selected fields C,... contain K, Tis referencing field will be assigned to K; when w is expression Ti.pfind(K) and the to-be-selected fields C,... contain K, ordinal numbers of K values in Ti will be assigned to K.

2(K1=w1,Ki=wi,w)

Ki=wi is an assignment expression. Generally, parameter wi can use expression Ti.find(Ki) or Ti.pfind(K), where Ti is a table sequence; when wi is expression Ti.find(Ki) and the to-be-selected fields C,... contain Ki, Ti’s referencing field will be assigned to Ki correspondingly; when wi is expression Ti.pfind(Ki) and the to-be-selected fields C,... contain Ki, ordinal numbers of Ki values in Ti will be assigned to Ki.

w is a filter expression; you can reference Ki in w.

3K:Ti

Ti is a table sequence. Compare Ki value in the entity table with key values of Ti and discard records whose Ki value does not match; when the to-be-selected fields C,... contain K, Ti’s referencing field will be assigned to K.

4K:Ti:null

Filter away all records that satisfy K: Ti.

5K:Ti:#

Locate records according to ordinal numbers, compare ordinal numbers of records in table sequence Ti according to the entity table’s K values, and discard non-matching records; when the to-be-selected fields C,... contain K, Ti’s referencing field will be assigned to K.

 

mcs

A multicursor generated from an entity table

Option:

@k

Perform matching using the multicursor’s first field of the key

@v

Generate a pure table sequence-based column-wise cursor, which has higher performance than regular cursors

@x

Automatically close the entity table after data is fetched from the cursor

@o

Do not merge zone tables but retrieve data according to the order of zone tables when T is a multizone composite table

@w

Used on a multizone composite table;

Perform update merge; when zone tables share a same key value, ignore the record contained in the zone table with a smaller number; segmentation is performed according to the way zone table 1 is split; retrieve a zone table after the first one wholly if they are small enough;

Handle the deletion mark and do not return records with a deletion mark to the cursor; but if the key value of a record with the deletion mark is unique in the multizone composite table, just retain it;

This option enables retrieving key field(s) as well as the deletion mark field, if there is one, forcefully

Return value:

A multicursor

Example:

 

A

 

1

for 100

 

2

=to(10000).new(#:k1,rand():c1).sort@o(k1)

Return a table sequence:

3

=to(10000).new(#:k1,rand(10000):c2).sort@o(k1)

Return a table sequence:

4

=to(10000).new(#:k1,rand()*1000:c3).sort@o(k1)

Return a table sequence:

5

=A2.cursor()

Return a cursor.

6

=A3.cursor()

Return a cursor.

7

=A4.cursor()

Return a cursor.

8

=file("D:\\cs1.ctx")

Generate a composite table file.

9

=A8.create(#k1,c1)

Create the composite table’s base table.

10

=A9.append(A5)

Append data in A5’s cursor to the base table.

11

=A9.attach(table1,c2)

Create attached table table1 on base table.

12

=A11.append(A6)

Append data in A6’s cursor to table1.

13

=A11.cursor@m(;;2)

Segment the attached table and return a multicursor.

14

=A9.attach(table2,c3)

Create attached table table2 on base table.

15

=A14.append(A7)

Append data in A7’s cursor to table2.

16

=A14.cursor@v(;;A13)

Segment table2 according to A13’s multicursor.

When T is a multizone composite table:

 

A

 

1

=connect("demo").cursor("select  EID,NAME from  employee")

 

2

=file("emp.ctx")

Generate a composite table file.

3

=A2.create@y(#EID,NAME)

Create the composite table’s base table.

4

=A3.append(A1)

Append data in A1’s cursor to the composite table’s base table.

5

=A4.cursor@m(;;3)

Generate a multicursor having 3 subcursors according to the composite table.

6

=connect("demo").cursor("select  EID,NAME,GENDER,SALARY  from  employee")

 

7

=file("emp.ctx":[1,2])

Generate a homo-name files group.

8

=A7.create@y(#EID,NAME,GENDER,SALARY;if(GENDER=="F",1,2))

Create a multizone composite table.

9

=A8.append@x(A6)

Append data in A6’s cursor to the multizone composite table and its content is as follows:

10

=A8.cursor(EID,NAME,GENDER,SALARY;SALARY>5000;A5)

Split A8’s multizone composite table synchronously according to A5’s multicursor, perform merge by default and return a cursor as follows:

We can see that data in two zone tables are merged by their dimensions.

11

=A8.cursor@o(EID,NAME,GENDER,SALARY;SALARY>5000;A5)

With @o option, do not perform merge but retrieve data from zone tables in order.

The upper half of the table is data in zone table 1 and the lower half is that in zone table 2.

Use special types of filtering conditions:

 

A

 

1

=file("emp.ctx")

 

2

=A1.open()

Open the composite table file.

3

=A2.import()

As no parameters are present, return all data in the entity table.

4

=file("emp1.ctx").open().cursor@m(;;2)

Return a multicursor.

5

=5.new(~:ID,~*~:Num).keys(ID)

Generate a table sequence using ID as the key.

6

=A2.cursor(EID,NAME;EID=A5.find(EID);A4)

Use K=w filtering mode; in this case w is Ti.find(K) and entity table records making EID=A4.find(EID) get null or false are discarded; EID is the selected field, to which table sequence A5’s referencing field is assigned.

7

=A2.cursor(EID,NAME;EID=A5.pfind(EID);A4)

Use K=w filtering mode; in this case w is Ti.pfind(K) and entity table records making EID=A4.pfind(EID) get null or false are discarded; EID is the selected field, to which its ordinal numbers in table sequence A5 are assigned.

8

=A2.cursor(EID,NAME;EID:A5;A4)

Use K:Ti filtering mode; compare the entity table’s EID values with the table sequence’s key values and discard entity table records that cannot match.

9

=A2.cursor(NAME,SALARY;EID:A5;A4)

This is a case where K isn’t selected; EID isn’t the selected field, so only filtering is performed.

10

=A2.cursor(EID,NAME;EID:A5:null;A4)

Use K:Ti:null filtering mode; compare the entity table’s EID values with the table sequence’s key values and discard entity table records that can match.

11

=A2.cursor(EID,NAME;EID:A5:#;A4)

Use K:Ti:# filtering mode; compare with ordinal numbers of table sequence’s records according to the entity table’s EID values, and discard records that cannot match.

12

=connect("demo").query("select top 2  NAME,GENDER  from employee").keys(NAME)

Return a table sequence using NAME as the key.

13

=A2.cursor(EID,NAME;(EID=A5.find(EID),NAME=A12.find(NAME),EID!=null

&&NAME!=null);A4)

Use (K1=w1,Ki=wi,w) filtering mode; return records that meet all conditions.

Use @w option to perform update merge:

 

A

 

1

=connect("demo").cursor("select  EID,NAME from  employee")

 

2

=file("e-mcs.ctx")

Generate a composite table file.

3

=A2.create@y(#EID,NAME)

Create the composite table’s base table.

4

=A3.append(A1)

Append cursor A1’s data to the composite table’s base table.

5

=A4.cursor@m(;;3)

Create a 3-subcursor multicursor based on the composite table.

6

=connect("demo").cursor("select  EID,NAME,GENDER  from employee") 

Return a cursor whose content is as follows:

7

=file("ec.ctx":[1,2])

Define a homo-name files group: 1.ec.ctx and 2.ec.ctx.

8

=A7.create@y(#EID,NAME,GENDER;if(GENDER=="F",1,2))

Create a multizone composite table, set EID as its key and put records where GENDER is F to 1.ec.ctx and the other records to 2.ec.ctx.

9

=A8.append@ix(A6)

Append cursor A6’s data to A8’s multizone composite table.

10

=create(EID,NAME,GENDER).record([1,"AAA","M"]).cursor()

Return a cursor whose content is as follows:

11

=file("ec.ctx":[3])

 

12

=A11.create@y(#EID,NAME,GENDER;3)

Add a new zone table 3.ec.ctx.

13

=A12.append@i(A10)

Append cursor A10’s data to zone table 3.ec.ctx; now both zone table 1.ec.ctx and zone table 3.ec.ctx have a record whose primary key is [1].

14

=file("ec.ctx":[1,2,3]).open()

Open multizone composite table ec.ctx.

15

=A14.cursor(;;A5).fetch()

Split A14’s multizone composite table synchronously according to multicursor A5, and return a cursor as follows:

16

=A14.cursor@w(;;A5).fetch()

Use @w option to perform update merge and return a cursor as follows:

Use @w option to recognize deletion mark:

 

A

 

1

=connect("demo").cursor("select  EID,NAME from  employee")

 

2

=file("e-mcs.ctx")

Generate a composite table file.

3

=A2.create@y(#EID,NAME)

Create the composite table’s base table.

4

=A3.append(A1)

Append cursor A1’s data to the composite table’s base table.

5

=A4.cursor@m(;;3)

Create a 3-subcursor multicursor based on the composite table.

6

=connect("demo").cursor("select  EID,NAME,GENDER  from employee") 

 

7

=A6.derive(false:Defiled)

 

8

=A7.new(EID,Defiled,NAME,GENDER)

Return a cursor whose content is as follows:

9

=file("ecd.ctx":[1,2])

Define a homo-name files group: 1.ec.ctx and 2.ec.ctx.

10

=A9.create@yd(#EID,Defiled,NAME,GENDER;if(GENDER=="F",1,2))

Create a multizone composite table, set EID as its key, use @d option to make Defiled as the deletion mark field, and put records where GENDER is F to 1.ed.ctx and the other records to 2.ed.ctx.

11

=A10.append@ix(A8)

Append cursor A8’s data to A10’s multizone composite table.

12

=create(EID,Defiled,NAME,GENDER).record([2,true,,,0,true,,]).cursor()

Return a cursor whose content is as follows:

13

=file("ecd.ctx":[3])

 

14

=A13.create@yd(#EID,Defiled,NAME,GENDER;3)

Add a new zone table 3.ecd.ctx, where Defiled is the deletion mark field.

15

=A14.append@i(A12)

Append cursor A1’s records to zone table 3.ecd.ctx where the deletion mark field value for record whose primary key is 2 is true and the record whose primary key value is 0 is new to the zone table.

16

=file("ecd.ctx":[1,2,3]).open()

 

17

=A16.cursor(;;A5)

Split A16’s multizone composite table synchronously according to multicursor A5, and return a multicursor.

18

=A17.fetch()

Fetch data from cursor A17.

19

=A16.cursor@w(;;A5)

Use @w option to split composite table ecd.ctx into multiple segments according to multicursor A5, return the segmented composite table as a multicursor, recognize the deletion mark – that is, won’t return the record whose primary key value is 2 to the result multicursor, and retain the record whose primary key value is unique though it is marked by a deletion mark – that is, return the record whose primary key value is 0 to the result multicursor; below is content of the multicursor:

20

=A19.fetch()

Fetch data from cursor A19.

T.cursor(x:C,…;wi,...;mcs)

Description:

Synchronously segment a cluster entity table according to a cluster multicursor and return a cluster multicursor.

Syntax:

T.cursor(x;C,…;wi;mcs)

Note:

The function synchronously segments cluster entity table T according to cluster multicursor mcs, during which T’s dimension and mcs’s key will be matched, and returns a cluster multicursor; the way of distributing T and mcs among nodes must be the same and the fields for segmenting T and mcs should be consistent. If multiple cluster entity tables are involved, use a cluster multicursor as a reference to make sure the segmentation is synchronous.

Parameter:

T

A cluster entity table

x

Expression

wi

Filtering condition; retrieve the whole set when this parameter is absent; separate multiple conditions by comma(s) and their relationships are AND

mcs

A cluster multicursor generated from a cluster entity table

Return value:

A cluster multicursor

Example:

 

A

 

1

=file("cs1.ctx":[1],"169.254.121.62:8281")

 

2

=A1.open()

Open a cluster composite table.

3

=A2.attach(table1)

Retrieve cluster entity table table1.

4

=A3.cursor@m(;;2)

Return a cluster multicursor.

5

=A2.attach(table2)

Retrieve cluster entity table table2.

6

=A5.cursor(;;A4)

Segment cluster entity table table2 according to table1’s multicursor; the two tables should use same segmenting field.

T.cursor()

Description:

Get a cursor based on a pseudo table object.

Syntax:

T.cursor(xi:Ci,…)

Note:

The function gets a cursor based on pseudo table T by specifying field expressions xi and field names Ci, which, by default, field names in the pseudo table. It gets a cursor using all fields of the pseudo table when paramters xi:Ci are absent.

Parameter:

T

A pseudo table

xi

A field expression

Ci

Field name in a result table sequence

Option:

@v

Store the composite table in the column-wise format when loading it the first time, which helps to increase performance

Return value:

A cursor

Example:

 

A

 

1

=create(file).record(["D:/file/pseudo/empT.ctx"])

 

2

=pseudo(A1)

Generate a pseudo table object.

3

=A2.cursor()

Generate a cursor from A2’s pseudo table using all its fields, since no parameters are present.

4

=A3.fetch()

Below is data in A3’s cursor:

5

=A2.cursor(EID:eid,NAME,SALARY:salary)

Retrieve fields EID, NAME and SALARY from the pseudo table to generate a cursor with new field names eid, NAME and salary respectively.

6

=A5.fetch()

Below is data in A5’s cursor:

 

mcs.cursor(n)

Description:

Merge subcursors in a multicursor into a unicursor or a new multicursor with a smaller number of parallel subcursors.

Syntax:

mcs.cursor(n)

Note:

The function merges subcursors in a multicursor into a unicursor, which is the default, or a new multicursor with a smaller number, which is specified by parameter n, of parallel subcursors.

Parameter:

mcs

A multicursor

n

Subcursor column name

Return value:

A common cursor or a multicursor

Example:

 

A

 

1

=demo.query("select * from EMPLOYEE").cursor@m(5)

Return a multicursor having 5 subcursors.

2

=A1.cursor(3)

Merge subcursors in the multicursor and convert it to a 3-subcursor multicursor.

3

=A2.cursor()

Convert a multicursor to a unicursor.