Size of Postgresql table - increased on table row or column?

Question

So I have a strange problem. Recently I came across a database structure that was something like this:

| salt @ 01:00 | salt @ 02:00 | salt @ 02:00 |
|:-------------|--------------|--------------|
|            0 |            3 |           2  |

Where each datestamp was a separate column. I didn't think such a structure was optimal, so I rearranged it to look something like this:

|    creation_time    |   salt   |
|:--------------------|----------|
| 2018-08-15 01:00:00 |        0 |
| 2018-08-15 02:00:00 |        3 |
| 2018-08-15 03:00:00 |        2 |

For some reason, this incredibly increases the size of the table. In one table, I went from having 3269 rows in the previous table to 5142823 rows, which is fine, but the size increased from 1048 kB to 674 MB.

So is this some kind of hack to reduce table size i.e. defining each creation_time as a column instead of including it in the row? Could I do anything to reduce the size?

Answer 1

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