ETS retrieve all objects before deleting the table

[Mikael Karlsson]

ets:foldl/3 maybe?

Den ons 19 jan. 2022 23:18Frank Muller <frank.muller.erl@REDACTED> skrev:

> Hi Valentin,
>
> Have you read what I posted in earlier messages?
> I already explored first/next with other alternatives.
>
> Thanks anyway
>
> /F.
>
>
>> In addition to serialisation to disk (its:tab2file/2,3), one can always
>> use:
>>
>> *ets:first/1* followed by a number of  calls to *ets:next/2*
>>
>>
>> e.g.
>>         ets:first( Tab ) -> Key
>> ets:lookup( Tab, Key ) -> [TableRow] % to retrieve data associated with
>> this key
>>         ets:next( Tab, Key ) -> NextKey, etc.
>>
>> NOTE: once the end of the table is reached, instead of a key an atom
>> ‘$end_of_table’ is returned by ets:next/2.
>>
>>
>> On 19 Jan 2022, at 23:33, valentin@REDACTED <valentin@REDACTED>
>> wrote:
>>
>> To serialize ETS to a file on the disk, one may use ets:tab2file/2,3.
>>
>> It does not destroy the table, but simply dumps a content of the table to
>> a file. I’ve used it a number of times and it works as advertised.
>> I don’t think there’s a tool available to traverse this file without
>> loading it back to ETS (via ets:file2tab/1,2).
>>
>> However, it may be a start.
>>
>>
>> V/
>>
>>
>>
>>
>> On 18 Jan 2022, at 17:02, Hugo Mills <hugo@REDACTED> wrote:
>>
>>  I may be wrong, but my reading of Frank's requirement was that the
>> table needs to be serialised to disk in some external format so that
>> it can be processed by some additional tool outside the current erlang
>> application. No amount of reparenting to another erlang process in the
>> same VM is going to accomplish that...
>>
>>  Hugo.
>>
>> On Tue, Jan 18, 2022 at 03:49:51PM +0200, Led wrote:
>>
>>
>> I think this opinion stems from confusion about the GiftData argument
>> in ets:give_away/3.
>>
>> AFAIK this just passes whatever 'data' you set for the variable, not
>> the actual table data, through to the recipient of the 'ETS_TRANSFER'
>> message.
>>
>>
>> It gives all table data with full access to the process "for
>> processing". What else do you need?
>>
>>
>> On Tue, Jan 18, 2022 at 7:28 AM Frank Muller <frank.muller.erl@REDACTED>
>> wrote:
>>
>>
>> No it doesn’t. It only charges the table owner
>>
>>
>>
>>
>> I’d like to retrieve all objects before deleting the table.
>>
>>
>> Strange task. Table is already "all objects".
>>
>>
>>
>> Nothing strange. Just a simple requirement.
>> Objects are sent elsewhere for processing before deleting the table
>> content.
>>
>>
>> What’s the most efficient way to do it?
>>
>>
>> ets:give_away/3
>>
>>
>>
>> That’s strange indeed. How give_away/3 could help? It gives the ownership
>> to another proc.
>>
>>
>> It actually sends all objects elsewhere (to another proc) for processing.
>>
>>
>> --
>> Hugo Mills             | All hope abandon, Ye who press Enter here.
>> hugo@REDACTED carfax.org.uk |
>> http://carfax.org.uk/  |
>> PGP: E2AB1DE4          |
>>
>>
>>
>>
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