append()

Read(2500) Label: append,

Here’s how to use append() functions.

T.append( cs )

Description:

Append records in a cursor/table sequence to an entity table.

Syntax:

T.append(cs)

Note:

The function append-writes records in cursor/table sequence cs to entity table T.

When T is a multizone composite table, cs can be a multicursor. Each part of the multicursor cs corresponds to one zone of T uniquely.

If a table has an attached table, appending data to the parent table requires that data be ordered by the key and be unique; otherwise, error will be reported.

The parent table can have records that don’t have matches in a sub table, but the opposite situation is not allowed; otherwise, the appending to an attached table will be disabled.

Parameter:

T

An entity table/multizone composite table

cs

A cursor/table sequence

Option:

@i

Real-time appending whenever a retrieval happens; force an appending when a composite table is closed; by default, an appending is executed only when there is a specified number of new records

@x

Calculate the zone table expression is at each append when appending data in a unicursor to a multizone composite table because the cursor could correspond to multiple zones

@m

Write data through merge-append; append data after the last record by default; do not support attached tables for the time being

@y

Read records of cs to form an in-memory zone table but do not write the data to the external storage; mutually exclusive with other options;

Return a multizone composite table consisting of the existing composite table and the in-memory zone table when T is a uni-composite table

Return value:

Entity table

Example:

Ø When parameter T is an entity table:

1

=create(k1,v1).record([1,10,2,20,3,30,4,40,10,100])

Create a table sequence

2

=create(k1,k2,v2).record([1,1,"a",3,1,"c"])

Create a table sequence

3

=create(k1,v3).record([1,"red",1,"blue",2,"red",2,

"yellow",2,"red",2,"red",4,"black",4,"red",4,"red",

4,"red",4,"red",4,"red",10,"red"])

Create a table sequence

4

=file("D:/ctb.ctx")

 

5

=A4.create(#k1,v1)

Create the composite table’s base table, where k1 is a dimension and v1 is the base table’s column

6

=A5.attach(table2,#k2,v2)

Add attached table table2 to A5’s base table; k1 and k2 are the attached table’s dimensions and v2 is its column

7

=A5.attach(table3,v3)

Add attached table table3 to A5’s base table; k1 is the attached table’s dimension and v3 is its column

8

=A5.append(A1.cursor())

Append cursor records to the base table

9

=A6.append(A2.cursor())

Append cursor records to attached table table2

10

=A7.append(A3.cursor())

Append cursor records to attached table table3

11

=A5.cursor().fetch()

Return data of the base table

12

=A6.cursor().fetch()

Return data of the attached table table2

13

=A7.cursor().fetch()

Return data of the attached table table3

 

Ø  When parameter T is a multizone composite table:

 

A

 

1

=connect("demo").cursor("select EID,NAME,GENDER,SALARY  from employee where GENDER='M' order by SALARY")

 

2

=connect("demo").cursor("select EID,NAME,GENDER,SALARY  from employee where GENDER='F' order by SALARY")

 

3

=[A1,A2].mcursor()

Return a multicursor

4

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

Generate a homo-name files group that contain two files 1.emp.ctx and 2.emp.ctx

5

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

Create a multizone composite table, where if(GENDER=="F",1,2) is a zone table expression, and @y optioin forces creating a new one even if the target file already exists

6

=A5.append@i(A3)

Append-write data in A3’s multicursor to A5’s multizone composite table (each part of the multicursor uniquely corresponds to a zone of the multizone composite table), where @i option enables an immediate append

 

Ø  When a unicursor is appended to a multizone composite table:

 

A

 

1

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

Return a unicursor

2

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

Generate a homo-name files group

3

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

Return a multizone composite table

4

=A3.append@x(A1)

Use @x to append data in the unicursor to the multizone composite table, where a zone table expression is calculated at each append

5

=A3.close()

Close the composite table

 

Ø  Merge-append:

 

A

 

1

=demo.query("select EID,NAME from employee where EID>495")

Return a table sequence

2

=file("apm.ctx")

 

3

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

Create a composite table

4

=A3.append(A1)

Append data of A1’s table sequence to the composite table

5

=create(EID,NAME).record([5,"Ashley"])

Return a table sequence

6

=A3.append@m(A5)

Append data of A5’s table sequence to the composite table; as @m option works, write data through merge-append

7

=A6.import()

Import data from the composite table:

8

>A3.close()

Close the composite table

 

Ø  Write data to the memory:

 

A

 

1

=demo.query("select EID,NAME from employee where EID>495")

Return a table sequence

2

=file("apm.ctx")

 

3

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

Create a composite table

4

=A3.append(A1)

Append table sequence A1’s data to the composite table

5

=create(EID,NAME).record([5,"Ashley"])

Return a table sequence

6

=A3.append@y(A5)

Append table sequence A5’s data to the composite table; @y option enables reading A5’s data, writing it to the memory and returning a multizone composite table consisting of the uni-composite table and the in-memory zone table

7

=A6.import()

View data in table A6, which contains A5’s data that has been appended

8

>A3.close()

Close the composite table

9

=A2.open().import()

As A6 uses @y option, the appended data isn’t written to the external memory and a view shows that the composite table does not contain A5’s data

T.append( cs )

Description:

Append-write records of a cursor to a pseudo table.

Syntax:

T.append(cs)

 

Note:

The function append-writes records of cursor cs to pseudo table T.

Parameter:

T

A pseudo table

cs

A cursor

Option:

@i

Append-write immediately at exit of the program or at retrieval while, by default, perform the operation when the number of records reaches to a specified number

@x

Calculate the zone table expression is at each append when append-writing data in a unicursor to a pseudo table whose source composite table is a multizone one because the cursor could correspond to multiple zones

@y

Write the appended records to the memory instead of keeping it in the external memory

Return value:

Pseudo table

Example:

Ø  Append-write to a pseudo table:

 

A

 

1

=create(file).record(["D:/file/Employee2.ctx"])

 

2

=pseudo(A1)

Generate a pseudo table object

3

=create(Dept,AvgSalary).record(["CSD",6400.53])

 

Create a table sequence

4

=A2.append@i(A3.cursor())

Append A3’s cursor record to the pseudo table

 

Ø  Append-write a unicursor to a pseudo table:

 

A

 

1

=file("append/apps.ctx":[1,2]).create@yi(#eid, deptid;(deptid%2)+1)

 

2

=to(1,10000).new(~:eid,rand(5)+1:deptid)

Create a table sequence

3

=pseudo(create(file,zone).record(["append/apps.ctx",[1,2]]))

Generate a pseudo table object

4

=A3.append@ix(A2.cursor())

With @x option, append-write A2’s unicursor to two zones of A3’s pseudo table by calculating the zone table expression at each append

 

Ø  Use @y option to write the appended records to the memory:

 

A

 

1

=create(file).record(["em.ctx"])

Return the pseudo table definition record

2

=pseudo(A1)

Generate a pseudo table definition object

3

=A2.import()

Read data from the pseudo table

4

=create(EID,NAME).record([0,"AAAA"])

Return a table sequence

5

=A2.append@y(A4.cursor())

Append table sequence A4’s records to pseudo table A2; @y option enables converting A4’s data to an in-memory zone table and writing it to the memory

6

=A2.import()

Import data from the pseudo table, where there are records appended in A5

7

>A2.close()

Close the pseudo table

8

=pseudo(A1).import()

Import data from pseudo table A1; as A5 uses @y option and the appended data isn’t written to the external memory, the imported pseudo table data here does not contain A4’s data; the result is the same as A3’s: