Does field_revision_field_xxx table store the same values as field_data_field_xxx does?

Question

I use drupal7.

According to the answer here,

• {field_data_[field_name]} Standard data storage for a field.
• {field_revision_[field_name]} Standard revision storage for a field.

I understand it, but, finally, they store the same values, right? This is because, I found that field_revision_field_xxx actually stores the updated values after I update a field-xxx.

[The reason why I ask this]
I try to transfer field values from one profile type to another which have the same uid. For it, I create field_data_field_xxx_transfered and field_revision_field_xxx_transfered and rewrite the pid in them.

I succeeded to transfer values from field_data_field_xxx to field_data_field_xxx_transfered. And, if field_revision_field_xxx stores the same values as field_data_field_xxx does, all I need to do is to copy field_data_field_xxx_transfered to field_revision_field_xxx_transfered. And, this is much easier than to do from field_revision_field_xxx to field_revision_field_xxx_transfered.

Thank you.

Answer 1

Yes, field_revision_[FIELD_NAME] contains the same value as field_data_[FIELD_NAME]. The only difference in both these table is, if you've enabled revision for entity having this field ([FIELD_NAME]), the field_data_[FIELD_NAME] will contain the latest revision value of the field and field_revision_[FIELD_NAME] will contain all revision value.

For example, Suppose I've a content type article with revision enabled, and has a field field_tags. I've then created a content of type article, so now field_data_field_tags and field_revision_field_tags contain data for the content I've just created. After this when ever I'll be updating this content, the field_data_field_tags will hold the latest revision data for field_tags field and field_revision_field_tags will hold all revision data for field_tags field i.e. revision id 1, 2, 3 and so on.