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upsert

Overwrite or append records to a table

x upsert y    upsert[x;y]

Where

  • x is a table, or the name of a table as a symbol atom, or the name of a splayed table as a directory handle
  • y is zero or more records

the records are upserted into the table.

The record/s y may be either

  • lists with types that match type each x cols x
  • a table with columns that are members of cols x and have corresponding types

If x is the name of a table, it is updated in place. Otherwise the updated table is returned.

If x is the name of a table as a symbol atom (or the name of a splayed table as a directory handle) that does not exist in the file system, it is written to file.

Simple table

If the table is simple, new records are appended. If the records are in a table, it must be simple.

q)t:([]name:`tom`dick`harry;age:28 29 30;sex:`M)

q)t upsert (`dick;49;`M)
name  age sex
-------------
tom   28  M
dick  29  M
harry 30  M
dick  49  M

q)t upsert((`dick;49;`M);(`jane;23;`F))
name  age sex
-------------
tom   28  M
dick  29  M
harry 30  M
dick  49  M
jane  23  F

q)`t upsert ([]age:49 23;name:`dick`jane)
`t
q)t
name  age sex
-------------
tom   28  M
dick  29  M
harry 30  M
dick  49
jane  23

Keyed table

If the table is keyed, any new records that match on key are updated. Otherwise, new records are inserted.

If the right argument is a table it may be keyed or unkeyed.

q)a upsert (`e;30;70)                         / single record
s| r  u
-| -----
q| 1  5
w| 2  6
e| 30 70

q)a upsert ((`e;30;70);(`r;40;80))            / multiple records
s| r  u
-| -----
q| 1  5
w| 2  6
e| 30 70
r| 40 80

q)show a:([]s:`q`w`e;r:1 2 3;u:5 6 7)         / simple table
s| r u
-| ---
q| 1 5
w| 2 6
e| 3 7

q)/update `q and `e, insert new `r; return new table
q)a upsert ([s:`e`r`q]r:30 4 10;u:70 8 50)    / keyed table
s| r  u                                       
-| -----
q| 10 50
w| 2  6
e| 30 70
r| 4  8

q)`a upsert ([s:`e`r`q]r:30 4 10;u:70 8 50)   / same but update table in place
`a

Serialized table

q)`:data/tser set ([] c1:`a`b; c2:1.1 2.2)
`:data/tser
q)`:data/tser upsert (`c; 3.3)
`:data/tser

q)get `:data/tser
c1 c2
------
a  1.1
b  2.2
c  3.3

Upserting to a serialized table reads the table into memory, updates it, and writes it back to file.

Splayed table

q)`:data/tsplay/ set ([] c1:`sym?`a`b; c2:1.1 2.2)
`:data/tsplay/
q)`:data/tsplay upsert (`sym?`c; 3.3)
`:data/tsplay
q)select from `:data/tsplay
c1 c2
------
a  1.1
b  2.2
c  3.3

Upserting to a splayed table appends new values to the column files.

Upserting to a serialized or splayed table removes any attributes set.

Cond is not supported inside q-SQL expressions

Enclose in a lambda or use Vector Conditional instead.

insert, Join
Joins, qSQL, Tables
Q for Mortals §9.2 Upsert

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