I got rid of the error two ways:
1. comment out the following line:
add_filter('post_limits', 'relevanssi_getLimit');
2. Leave the previous line as-is, but add back this function (taken from 2.9.1) that is no longer in 2.9.2:
// This function is from Kenny Katzgrau
function relevanssi_getLimit($limit) {
global $wpSearch_low;
global $wpSearch_high;
if(is_search()) {
$temp = str_replace("LIMIT", "", $limit);
$temp = explode(",", $temp);
$wpSearch_low = intval($temp[0]);
if ($wpSearch_high == 0) {
$wpSearch_high = intval($wpSearch_low + intval($temp[1]) - 1);
}
}
return $limit;
}
I haven't decided which to go with for sure, but either one stops the error appearing (and fixes another problem I have with version 2.9.2 of the plugin).