How to modify ttl using UDF


#1

FAQ - How to modify the ttl using an UDF

Context

Objects can have a ttl (time to live) set which means that they will expire (deleted) when after the ttl is reached. Objects can also never expire if their ttl is set to -1 (will cause server to set the ttl to 0 – setting the ttl to 0 from the client policy would cause the server to use the configured default-ttl).

Refer to this FAQ ttl for details about the TTL.

Method

Use the record.set_ttl() and aerospike:update() methods to set a ttl. Here is an example:

1. ttl.lua script to set record’s ttl to 1 day (86400 seconds):

function expireRecord(rec)
        local currTTL = record.ttl(rec)
        if ( currTTL == 0 ) then
                record.set_ttl(rec, 86400)
                local result = aerospike:update(rec)
                if ( result ~= nil and result ~= 0 ) then
                        warn("expireRecord:Failed to UPDATE the record: resultCode (%s)", tostring(result))
                end
        end
end

2. Run the following commands in aql to create two non-expirable records:

aql> set RECORD_TTL -1
RECORD_TTL = -1
aql> insert into test.demoset (PK, name) VALUES (101, 'name1');
OK, 1 record affected.

aql> insert into test.demoset (PK, name) VALUES (102, 'name2');
OK, 1 record affected.

3. Run the following commands to create two records that will expire in 1000 seconds:

aql> set RECORD_TTL 1000
RECORD_TTL = 1000
aql> insert into test.demoset (PK, name) VALUES (103, 'name3');
OK, 1 record affected.

aql> insert into test.demoset (PK, name) VALUES (104, 'name4');
OK, 1 record affected.

4. Confirm the data

aql> set RECORD_PRINT_METADATA true
RECORD_PRINT_METADATA = true
aql> select * from test.demoset
+---------+--------------------------------+-----------+-------+-------+
| name    | {edigest}                      | {set}     | {ttl} | {gen} |
+---------+--------------------------------+-----------+-------+-------+
| "name2" | "CaRk4OUs2Xm+7Wzbz93Tz7b0cdg=" | "demoset" | -1    | 1     |
| "name3" | "8lU4X7fI8SrbLDuoAeshW9CCphs=" | "demoset" | 986   | 1     |
| "name4" | "RxiiUM398Ycwg1amNhlh8qfSsgA=" | "demoset" | 991   | 1     |
| "name1" | "bcpatNmxoJ53HxWz3EkD/TSMCQ4=" | "demoset" | -1    | 1     |
+---------+--------------------------------+-----------+-------+-------+
4 rows in set (0.170 secs)

OK

5. Apply the lua script:

aql> register module 'ttl.lua'
OK, 1 module added.

aql> execute ttl.expireRecord() on test.demoset
OK, Scan job (12893429980729116258) created.

6. Confirm that only the non-expirable records are updated (with generation incremented):

aql> select * from test.demoset
+---------+--------------------------------+-----------+-------+-------+
| name    | {edigest}                      | {set}     | {ttl} | {gen} |
+---------+--------------------------------+-----------+-------+-------+
| "name2" | "CaRk4OUs2Xm+7Wzbz93Tz7b0cdg=" | "demoset" | 86395 | 2     |
| "name3" | "8lU4X7fI8SrbLDuoAeshW9CCphs=" | "demoset" | 968   | 1     |
| "name4" | "RxiiUM398Ycwg1amNhlh8qfSsgA=" | "demoset" | 973   | 1     |
| "name1" | "bcpatNmxoJ53HxWz3EkD/TSMCQ4=" | "demoset" | 86395 | 2     |
+---------+--------------------------------+-----------+-------+-------+
4 rows in set (0.166 secs)

OK

Notes

  1. While aql (or client) shows the ttl as -1 (no expiration), it is actually set to 0 on the server. You cannot set it to 0 to expire immediately but intepret as using the server default.

  2. The ttl is capped at 10 years as of version 3.8.3. There following errors will occur when attempting to set a higher value:

Oct 12 2018 17:42:13 GMT: WARNING (udf): (udf_aerospike.c:524) invalid ttl 3153600000
Oct 12 2018 17:42:13 GMT: WARNING (udf): (udf_aerospike.c:859) udf_aerospike_rec_update: failure executing record updates (-1)
Oct 12 2018 17:42:13 GMT: WARNING (udf): (/opt/aerospike/usr/udf/lua/ttl.lua:55) expireNextCentury:Failed to UPDATE the record: resultCode (-1)
  1. Refer to the following articles for impact of cold restart on deleted records (which have not expired):
  1. Refer to the UDF Management article for details on managing UDF modules in Aerospike.

Keywords

UDF TTL NON-EXPIRABLE OBJECTS

Timestamp

11/13/2018


Setting time-to-live(ttl)
FAQ - Understanding time to live on an Aerospike cluster