Adding new field to big table

Hello,

I'm having time issues when adding new fields to a big table. I hope you can point me some hints to speed up the updates of a table with 124 million rows...

This is what I do:

First I create a tmp_table with the data that will be added to the big table:

\d+ svm_confidence_id_tmp
Table "public.svm_confidence_id_tmp"
Column | Type | Modifiers | Storage | Stats target | Description
---------------+------------------+-----------+---------+--------------+-------------
id | integer | not null | plain | |
svmconfidence | double precision | | plain | |
Indexes:
"svm_confidence_id_tmp_pkey" PRIMARY KEY, btree (id)

The table where this data will be added has the svmConfidence field

\d+ document;
Table "public.document"
Column | Type | Modifiers | Storage | Stats target | Description
------------------+--------------------------------+-----------+----------+--------------+-------------
id | integer | not null | plain | |
kind | character varying(255) | not null | extended | |
uid | character varying(255) | not null | extended | |
sentenceId | character varying(255) | not null | extended | |
text | text | not null | extended | |
hepval | double precision | | plain | |
created | timestamp(0) without time zone | not null | plain | |
updated | timestamp(0) without time zone | | plain | |
cardval | double precision | | plain | |
nephval | double precision | | plain | |
phosval | double precision | | plain | |
patternCount | double precision | | plain | |
ruleScore | double precision | | plain | |
hepTermNormScore | double precision | | plain | |
hepTermVarScore | double precision | | plain | |
svm | double precision | | plain | |
svmConfidence | double precision | | plain | |
Indexes:
"DocumentOLD_pkey" PRIMARY KEY, btree (id)
"document_cardval_index" btree (cardval)
"document_heptermnorm_index" btree ("hepTermNormScore" DESC NULLS LAST)
"document_heptermvar_index" btree ("hepTermVarScore" DESC NULLS LAST)
"document_hepval_index" btree (hepval DESC NULLS LAST)
"document_kind_index" btree (kind)
"document_nephval_index" btree (nephval DESC NULLS LAST)
"document_patterncount_index" btree ("patternCount" DESC NULLS LAST)
"document_phosval_index" btree (phosval DESC NULLS LAST)
"document_rulescore_index" btree ("ruleScore" DESC NULLS LAST)
"document_sentenceid_index" btree ("sentenceId")
"document_svm_index" btree (svm)
"document_uid_index" btree (uid)

Then I update the svmConfidence field of the document table like this:

update document as d set "svmConfidence" = st.svmconfidence from svm_confidence_id_tmp as st where st.id = d.id;

But it takes too much time.
Is there something to take into account? Any hints?
Should I do it in a different way?

Thanks for your time...

Andrés
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