pgsql: Use read streams in CREATE DATABASE when STRATEGY=WAL_LOG.

Use read streams in CREATE DATABASE when STRATEGY=WAL_LOG.

While this doesn't significantly change runtime now, it arranges for
STRATEGY=WAL_LOG to benefit automatically from future optimizations to
the read_stream subsystem.  For large tables in the template database,
this does read 16x as many bytes per system call.  Platforms with high
per-call overhead, if any, may see an immediate benefit.

Nazir Bilal Yavuz

Discussion: https://postgr.es/m/CAN55FZ0JKL6vk1xQp6rfOXiNFV1u1H0tJDPPGHWoiO3ea2Wc=A@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/8720a15e9ab121e49174d889eaeafae8ac89de7b

Modified Files
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src/backend/storage/buffer/bufmgr.c | 53 ++++++++++++++++++++++++++++++++++---
1 file changed, 49 insertions(+), 4 deletions(-)