How to modify a record ttl on a non-expirable record using a 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).
We will use the record.set_ttl() and aerospike:update() methods to set a ttl. Reter to this page https://www.aerospike.com/docs/udf/api/record.html#record-set_ttl- for details. 
 

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Method

 

1. Create a lua file similar to ttl.lua script to set record's ttl to 1 day (86400 seconds) for non-expirable records:

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. Verify current record TTL 

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

3. Register and Apply the lua UDF script:

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

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

4. Confirm the record TTLon non-expirable records has been updated. (gen number also 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

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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 this is  interpreted as using the server default.

2. The ttl is capped at 10 years. 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)

3. Refer to the following articles for impact of cold restart on deleted records (which have not expired):

• Cold Restart Details

4. Refer to the UDF Management article for details on managing UDF modules in Aerospike.

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Applies To Earliest Version

Pre 4.9

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Applies To Latest Version

Current Version

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