The 4th alpha resease of OrioleDB incorporates the following fixes.

• Merge sparse pages during checkpoint
• Fix runXmin overrun
• Fix page corruption + page structure check
• Use repalloc_huge() for an array of downlinks during tree scan
• Missing advance_oxids() in read_xids()
• Fix race condition between advance_global_xmin() and set_oxid_csn()
• GUC for default compression levels
• Show compression levels in table description
• Remove old tmp files during normal restart
• Fix interlock between write_xidsmap() and advance_global_xmin()
• Fix checkpoint writeback concurrency

The sponsors of this release are:

• Ian Livingstone (@ianlivingstone),
• Michail Nikolaev (@michail-nikolaev).