Created attachment 84830 [details]
Sample database with high-precision data

Brief description:

In Base, copying a table or query with standard "Copy", the data are only copied to the precision defined by the formatting, not the full precision. For instance, standard numeric format shows two decimal places, so a data entry containing the number 3.1415 will be copied as 3.14, resulting in loss of precision.

It is suggested to replace the function "Copy" (in Base) by two functions:
1. "Copy as shown": Same behaviour as current "Copy".
2. "Copy with full precision": Copy with full precision.


More details:

For seeing the behaviour, open the attached small database and copy "Table1" into e.g. a Calc spreadsheet. The database contains the data

    MyTimestamp            MyDouble
    01-01-2015 00:00:01    1.2345
    01-01-2015 00:00:15    3.1415

but unless formatting is changed in Base before copying, "Copy" will only copy the timestamp to the level of full minutes, and the numbers will only be copied with two decimal places. (Changing formatting in Calc does not alter the data copied.)

As discussed in the closed Issue 126404, this behaviour has both advantages and disadvantages:

Advantage: Copying a full table can mean copying a huge amount of data to the clipboard. And copying data with full precision can give a confusing result on insert.

Disadvantages: The user is not warned that "Copy" is a lossy copy. The behaviour is different from "Copy" in Calc, where data is copied in full precison regardless of formatting for showing. Finally, alternatives for copying with full precision may not be obvious to the user.

Replacing "Copy" with "Copy as shown" will make more clear to the user that precision may be lost. And adding the choice "Copy with full precision" will make the alternative readily accessible, moving the responsibility for copying large tables to the user (where responsibility belongs).