PD and ES of History wanted to get a dump of the 1901 Census. They tried using the Export feature on the site, but all they got was a white, empty window when they executed it. Looks like the number of records they were trying to export (about 46,000) exceed some RAM or processing time limit in php, so the job was never returned, resulting in the white window. I did a query to export all the males, then all the females. Those two exports worked. I then combined the two into one big spreadsheet file.
I then went into phppgadmin and discovered there were 5 records unaccounted for. Those had a value of 9 in the sex field. I then went back to the website GUI and searched for each of those five records and then incorporated them into the spreadsheet.
So, I did get the client what they asked for by a workaround, but didn't precisely identify the cause of the problem, let alone a solution.