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[taler-exchange] 01/03: postgres documentation suggests to avoid 'FOR UP
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From: |
gnunet |
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Subject: |
[taler-exchange] 01/03: postgres documentation suggests to avoid 'FOR UPDATE' with serializable transactions |
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Date: |
Mon, 10 Aug 2020 08:15:30 +0200 |
This is an automated email from the git hooks/post-receive script.
grothoff pushed a commit to branch master
in repository exchange.
commit c2a0196f16d24bc5c80ec99e13487a337ffb347b
Author: Christian Grothoff <christian@grothoff.org>
AuthorDate: Sat Aug 8 20:01:56 2020 +0200
postgres documentation suggests to avoid 'FOR UPDATE' with serializable
transactions
---
src/exchangedb/plugin_exchangedb_postgres.c | 49 +++++++++++------------------
1 file changed, 19 insertions(+), 30 deletions(-)
diff --git a/src/exchangedb/plugin_exchangedb_postgres.c
b/src/exchangedb/plugin_exchangedb_postgres.c
index 7934639b..1cb10ea8 100644
--- a/src/exchangedb/plugin_exchangedb_postgres.c
+++ b/src/exchangedb/plugin_exchangedb_postgres.c
@@ -254,6 +254,10 @@ postgres_get_session (void *cls)
GNUNET_PQ_make_try_execute ("SET auto_explain.log_min_duration=50;"),
GNUNET_PQ_make_try_execute ("SET auto_explain.log_timing=TRUE;"),
GNUNET_PQ_make_try_execute ("SET auto_explain.log_analyze=TRUE;"),
+ /* https://wiki.postgresql.org/wiki/Serializable suggests to really
+ force the default to 'serializable' if SSI is to be used. */
+ GNUNET_PQ_make_try_execute (
+ "SET SESSION CHARACTERISTICS AS TRANSACTION ISOLATION LEVEL
SERIALIZABLE;"),
GNUNET_PQ_make_try_execute ("SET enable_sort=OFF;"),
GNUNET_PQ_make_try_execute ("SET enable_seqscan=OFF;"),
GNUNET_PQ_EXECUTE_STATEMENT_END
@@ -356,8 +360,7 @@ postgres_get_session (void *cls)
",gc_date"
" FROM reserves"
" WHERE reserve_pub=$1"
- " LIMIT 1"
- " FOR UPDATE;",
+ " LIMIT 1;",
1),
/* Used in #postgres_reserves_in_insert() when the reserve is new */
GNUNET_PQ_make_prepare ("reserve_create",
@@ -461,8 +464,7 @@ postgres_get_session (void *cls)
",execution_date"
",sender_account_details"
" FROM reserves_in"
- " WHERE reserve_pub=$1"
- " FOR UPDATE;",
+ " WHERE reserve_pub=$1;",
1),
/* Lock withdraw table; NOTE: we may want to eventually shard the
deposit table to avoid this lock being the main point of
@@ -507,8 +509,7 @@ postgres_get_session (void *cls)
" FROM reserves_out"
" JOIN denominations denom"
" USING (denom_pub_hash)"
- " WHERE h_blind_ev=$1"
- " FOR UPDATE;",
+ " WHERE h_blind_ev=$1;",
1),
/* Used during #postgres_get_reserve_history() to
obtain all of the /reserve/withdraw operations that
@@ -528,8 +529,7 @@ postgres_get_session (void *cls)
" FROM reserves_out"
" JOIN denominations denom"
" USING (denom_pub_hash)"
- " WHERE reserve_pub=$1"
- " FOR UPDATE",
+ " WHERE reserve_pub=$1;",
1),
/* Used in #postgres_select_withdrawals_above_serial_id() */
GNUNET_PQ_make_prepare ("audit_get_reserves_out_incr",
@@ -564,8 +564,7 @@ postgres_get_session (void *cls)
" denom_pub_hash"
",denom_sig"
" FROM known_coins"
- " WHERE coin_pub=$1"
- " FOR UPDATE;",
+ " WHERE coin_pub=$1;",
1),
/* Used in #postgres_get_coin_denomination() to fetch
the denomination public key hash for
@@ -701,8 +700,7 @@ postgres_get_session (void *cls)
" JOIN denominations denom "
" USING (denom_pub_hash)"
" WHERE rc=$1"
- " ORDER BY freshcoin_index ASC"
- " FOR UPDATE;",
+ " ORDER BY freshcoin_index ASC;",
1),
/* Used in #postgres_insert_refresh_reveal() to store the transfer
@@ -830,8 +828,7 @@ postgres_get_session (void *cls)
" JOIN denominations USING (denom_pub_hash)"
" WHERE ((coin_pub=$1)"
" AND (merchant_pub=$3)"
- " AND (h_contract_terms=$2))"
- " FOR UPDATE;",
+ " AND (h_contract_terms=$2));",
3),
/* Fetch deposits with rowid '\geq' the given parameter */
GNUNET_PQ_make_prepare ("audit_get_deposits_incr",
@@ -970,8 +967,7 @@ postgres_get_session (void *cls)
" USING (coin_pub)"
" JOIN denominations denom"
" USING (denom_pub_hash)"
- " WHERE coin_pub=$1"
- " FOR UPDATE;",
+ " WHERE coin_pub=$1;",
1),
/* Used in #postgres_get_link_data(). */
@@ -1282,8 +1278,7 @@ postgres_get_session (void *cls)
" USING (coin_pub)"
" JOIN reserves_out ro"
" USING (h_blind_ev)"
- " WHERE ro.reserve_pub=$1"
- " FOR UPDATE;",
+ " WHERE ro.reserve_pub=$1;",
1),
/* Used in #postgres_get_coin_transactions() to obtain recoup
transactions
affecting old coins of refreshed coins */
@@ -1306,8 +1301,7 @@ postgres_get_session (void *cls)
" FROM refresh_commitments"
" JOIN refresh_revealed_coins rrc"
" USING (rc)"
- " WHERE old_coin_pub=$1)"
- " FOR UPDATE;",
+ " WHERE old_coin_pub=$1);",
1),
/* Used in #postgres_get_reserve_history() */
GNUNET_PQ_make_prepare ("close_by_reserve",
@@ -1320,8 +1314,7 @@ postgres_get_session (void *cls)
",receiver_account"
",wtid"
" FROM reserves_close"
- " WHERE reserve_pub=$1"
- " FOR UPDATE",
+ " WHERE reserve_pub=$1;",
1),
/* Used in #postgres_get_expired_reserves() */
GNUNET_PQ_make_prepare ("get_expired_reserves",
@@ -1355,8 +1348,7 @@ postgres_get_session (void *cls)
" USING (h_blind_ev)"
" JOIN known_coins coins"
" USING (coin_pub)"
- " WHERE recoup.coin_pub=$1"
- " FOR UPDATE;",
+ " WHERE recoup.coin_pub=$1;",
1),
/* Used in #postgres_get_coin_transactions() to obtain recoup
transactions
for a refreshed coin */
@@ -1378,8 +1370,7 @@ postgres_get_session (void *cls)
" ON (rrc.rc = rc.rc)"
" JOIN known_coins coins"
" USING (coin_pub)"
- " WHERE coin_pub=$1"
- " FOR UPDATE;",
+ " WHERE coin_pub=$1;",
1),
/* Used in #postgres_get_reserve_by_h_blind() */
GNUNET_PQ_make_prepare ("reserve_by_h_blind",
@@ -1387,8 +1378,7 @@ postgres_get_session (void *cls)
" reserve_pub"
" FROM reserves_out"
" WHERE h_blind_ev=$1"
- " LIMIT 1"
- " FOR UPDATE;",
+ " LIMIT 1;",
1),
/* Used in #postgres_get_old_coin_by_h_blind() */
GNUNET_PQ_make_prepare ("old_coin_by_h_blind",
@@ -1398,8 +1388,7 @@ postgres_get_session (void *cls)
" JOIN refresh_commitments rcom"
" USING (rc)"
" WHERE h_coin_ev=$1"
- " LIMIT 1"
- " FOR UPDATE;",
+ " LIMIT 1;",
1),
/* used in #postgres_commit */
GNUNET_PQ_make_prepare ("do_commit",
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