Re: lag() default value ignored for some window partition depending on table records count?

- For every of this date/numeric couple within their "window partitioning", we need to determine the preceding value, thus the use of lag(<value>, 1, 0::numeric), since it's relevant for us here to get the very first record of the partition having "0.00" as its preceding value;

- Except that the "first" row of some partitions gets NULL instead of 0::numeric as the result of lag(<value>, 1, 0::numeric), while other get 0::numeric as expected;

- Things get stranger when the table containing the data get "purged" from every record except those corresponding to the "window partition" whose first record gets NULL as lag() output: now it also gets 0::numeric...

- "Odd" behavior may be seen for particular window partition when row count ∼ 600k, but not when only relevant rows (58 records) are kept;