This directory contains a general purpose data structures, for use anywhere
in the backend:
binaryheap.c - a binary heap
bipartite_match.c - Hopcroft-Karp maximum cardinality algorithm for bipartite graphs
bloomfilter.c - probabilistic, space-efficient set membership testing
dshash.c - concurrent hash tables backed by dynamic shared memory areas
hyperloglog.c - a streaming cardinality estimator
ilist.c - single and double-linked lists
integerset.c - a data structure for holding large set of integers
knapsack.c - knapsack problem solver
pairingheap.c - a pairing heap
rbtree.c - a red-black tree
stringinfo.c - an extensible string type
Aside from the inherent characteristics of the data structures, there are a
few practical differences between the binary heap and the pairing heap. The
binary heap is fully allocated at creation, and cannot be expanded beyond the
allocated size. The pairing heap on the other hand has no inherent maximum
size, but the caller needs to allocate each element being stored in the heap,
while the binary heap works with plain Datums or pointers.
The linked-lists in ilist.c can be embedded directly into other structs, as
opposed to the List interface in nodes/pg_list.h.
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